Cleanup: Fix up some diagnostics
diff --git a/compiler/rustc_infer/messages.ftl b/compiler/rustc_infer/messages.ftl
index 8f1c4ad..fbe8d31 100644
--- a/compiler/rustc_infer/messages.ftl
+++ b/compiler/rustc_infer/messages.ftl
@@ -104,10 +104,10 @@
 infer_consider_specifying_length = consider specifying the actual array length
 infer_data_flows = ...but data{$label_var1_exists ->
     [true] {" "}from `{$label_var1}`
-    *[false] -> {""}
+    *[false] {""}
 } flows{$label_var2_exists ->
     [true] {" "}into `{$label_var2}`
-    *[false] -> {""}
+    *[false] {""}
 } here
 
 infer_data_lifetime_flow = ...but data with one lifetime flows into the other here
diff --git a/compiler/rustc_lint/messages.ftl b/compiler/rustc_lint/messages.ftl
index 6f6480a..8b1a9a1 100644
--- a/compiler/rustc_lint/messages.ftl
+++ b/compiler/rustc_lint/messages.ftl
@@ -627,7 +627,7 @@
     .label = pattern not allowed in foreign function
 
 lint_private_extern_crate_reexport =
-    extern crate `{$ident}` is private, and cannot be re-exported (error E0365), consider declaring with `pub`
+    extern crate `{$ident}` is private, and cannot be re-exported, consider declaring with `pub`
 
 lint_proc_macro_back_compat = using an old version of `{$crate_name}`
     .note = older versions of the `{$crate_name}` crate will stop compiling in future versions of Rust; please update to `{$crate_name}` v{$fixed_version}, or switch to one of the `{$crate_name}` alternatives
diff --git a/compiler/rustc_lint/src/lints.rs b/compiler/rustc_lint/src/lints.rs
index 3bd6fac..51f58e3 100644
--- a/compiler/rustc_lint/src/lints.rs
+++ b/compiler/rustc_lint/src/lints.rs
@@ -2227,7 +2227,7 @@
 pub struct UnusedMacroUse;
 
 #[derive(LintDiagnostic)]
-#[diag(lint_private_extern_crate_reexport)]
+#[diag(lint_private_extern_crate_reexport, code = E0365)]
 pub struct PrivateExternCrateReexport {
     pub ident: Ident,
 }
diff --git a/compiler/rustc_mir_build/messages.ftl b/compiler/rustc_mir_build/messages.ftl
index 0bb44db..67e1e15 100644
--- a/compiler/rustc_mir_build/messages.ftl
+++ b/compiler/rustc_mir_build/messages.ftl
@@ -335,12 +335,12 @@
 mir_build_unsafe_not_inherited = items do not inherit unsafety from separate enclosing items
 
 mir_build_unsafe_op_in_unsafe_fn_borrow_of_layout_constrained_field_requires_unsafe =
-    borrow of layout constrained field with interior mutability is unsafe and requires unsafe block (error E0133)
+    borrow of layout constrained field with interior mutability is unsafe and requires unsafe block
     .note = references to fields of layout constrained fields lose the constraints. Coupled with interior mutability, the field can be changed to invalid values
     .label = borrow of layout constrained field with interior mutability
 
 mir_build_unsafe_op_in_unsafe_fn_call_to_fn_with_requires_unsafe =
-    call to function `{$function}` with `#[target_feature]` is unsafe and requires unsafe block (error E0133)
+    call to function `{$function}` with `#[target_feature]` is unsafe and requires unsafe block
     .help = in order for the call to be safe, the context requires the following additional target {$missing_target_features_count ->
         [1] feature
         *[count] features
@@ -355,48 +355,47 @@
     .label = call to function with `#[target_feature]`
 
 mir_build_unsafe_op_in_unsafe_fn_call_to_unsafe_fn_requires_unsafe =
-    call to unsafe function `{$function}` is unsafe and requires unsafe block (error E0133)
+    call to unsafe function `{$function}` is unsafe and requires unsafe block
     .note = consult the function's documentation for information on how to avoid undefined behavior
     .label = call to unsafe function
 
 mir_build_unsafe_op_in_unsafe_fn_call_to_unsafe_fn_requires_unsafe_nameless =
-    call to unsafe function is unsafe and requires unsafe block (error E0133)
+    call to unsafe function is unsafe and requires unsafe block
     .note = consult the function's documentation for information on how to avoid undefined behavior
     .label = call to unsafe function
 
 mir_build_unsafe_op_in_unsafe_fn_deref_raw_pointer_requires_unsafe =
-    dereference of raw pointer is unsafe and requires unsafe block (error E0133)
+    dereference of raw pointer is unsafe and requires unsafe block
     .note = raw pointers may be null, dangling or unaligned; they can violate aliasing rules and cause data races: all of these are undefined behavior
     .label = dereference of raw pointer
 
 mir_build_unsafe_op_in_unsafe_fn_extern_static_requires_unsafe =
-    use of extern static is unsafe and requires unsafe block (error E0133)
+    use of extern static is unsafe and requires unsafe block
     .note = extern statics are not controlled by the Rust type system: invalid data, aliasing violations or data races will cause undefined behavior
     .label = use of extern static
 
 mir_build_unsafe_op_in_unsafe_fn_initializing_type_with_requires_unsafe =
-    initializing type with `rustc_layout_scalar_valid_range` attr is unsafe and requires unsafe
-    block (error E0133)
+    initializing type with `rustc_layout_scalar_valid_range` attr is unsafe and requires unsafe block
     .note = initializing a layout restricted type's field with a value outside the valid range is undefined behavior
     .label = initializing type with `rustc_layout_scalar_valid_range` attr
 
 mir_build_unsafe_op_in_unsafe_fn_inline_assembly_requires_unsafe =
-    use of inline assembly is unsafe and requires unsafe block (error E0133)
+    use of inline assembly is unsafe and requires unsafe block
     .note = inline assembly is entirely unchecked and can cause undefined behavior
     .label = use of inline assembly
 
 mir_build_unsafe_op_in_unsafe_fn_mutable_static_requires_unsafe =
-    use of mutable static is unsafe and requires unsafe block (error E0133)
+    use of mutable static is unsafe and requires unsafe block
     .note = mutable statics can be mutated by multiple threads: aliasing violations or data races will cause undefined behavior
     .label = use of mutable static
 
 mir_build_unsafe_op_in_unsafe_fn_mutation_of_layout_constrained_field_requires_unsafe =
-    mutation of layout constrained field is unsafe and requires unsafe block (error E0133)
+    mutation of layout constrained field is unsafe and requires unsafe block
     .note = mutating layout constrained fields cannot statically be checked for valid values
     .label = mutation of layout constrained field
 
 mir_build_unsafe_op_in_unsafe_fn_union_field_requires_unsafe =
-    access to union field is unsafe and requires unsafe block (error E0133)
+    access to union field is unsafe and requires unsafe block
     .note = the field may not be properly initialized: using uninitialized data will cause undefined behavior
     .label = access to union field
 
diff --git a/compiler/rustc_mir_build/src/errors.rs b/compiler/rustc_mir_build/src/errors.rs
index e2a2846..38e6c00 100644
--- a/compiler/rustc_mir_build/src/errors.rs
+++ b/compiler/rustc_mir_build/src/errors.rs
@@ -21,7 +21,7 @@
 }
 
 #[derive(LintDiagnostic)]
-#[diag(mir_build_unsafe_op_in_unsafe_fn_call_to_unsafe_fn_requires_unsafe)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_call_to_unsafe_fn_requires_unsafe, code = E0133)]
 #[note]
 pub struct UnsafeOpInUnsafeFnCallToUnsafeFunctionRequiresUnsafe {
     #[label]
@@ -32,7 +32,7 @@
 }
 
 #[derive(LintDiagnostic)]
-#[diag(mir_build_unsafe_op_in_unsafe_fn_call_to_unsafe_fn_requires_unsafe_nameless)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_call_to_unsafe_fn_requires_unsafe_nameless, code = E0133)]
 #[note]
 pub struct UnsafeOpInUnsafeFnCallToUnsafeFunctionRequiresUnsafeNameless {
     #[label]
@@ -42,7 +42,7 @@
 }
 
 #[derive(LintDiagnostic)]
-#[diag(mir_build_unsafe_op_in_unsafe_fn_inline_assembly_requires_unsafe)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_inline_assembly_requires_unsafe, code = E0133)]
 #[note]
 pub struct UnsafeOpInUnsafeFnUseOfInlineAssemblyRequiresUnsafe {
     #[label]
@@ -52,7 +52,7 @@
 }
 
 #[derive(LintDiagnostic)]
-#[diag(mir_build_unsafe_op_in_unsafe_fn_initializing_type_with_requires_unsafe)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_initializing_type_with_requires_unsafe, code = E0133)]
 #[note]
 pub struct UnsafeOpInUnsafeFnInitializingTypeWithRequiresUnsafe {
     #[label]
@@ -62,7 +62,7 @@
 }
 
 #[derive(LintDiagnostic)]
-#[diag(mir_build_unsafe_op_in_unsafe_fn_mutable_static_requires_unsafe)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_mutable_static_requires_unsafe, code = E0133)]
 #[note]
 pub struct UnsafeOpInUnsafeFnUseOfMutableStaticRequiresUnsafe {
     #[label]
@@ -72,7 +72,7 @@
 }
 
 #[derive(LintDiagnostic)]
-#[diag(mir_build_unsafe_op_in_unsafe_fn_extern_static_requires_unsafe)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_extern_static_requires_unsafe, code = E0133)]
 #[note]
 pub struct UnsafeOpInUnsafeFnUseOfExternStaticRequiresUnsafe {
     #[label]
@@ -82,7 +82,7 @@
 }
 
 #[derive(LintDiagnostic)]
-#[diag(mir_build_unsafe_op_in_unsafe_fn_deref_raw_pointer_requires_unsafe)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_deref_raw_pointer_requires_unsafe, code = E0133)]
 #[note]
 pub struct UnsafeOpInUnsafeFnDerefOfRawPointerRequiresUnsafe {
     #[label]
@@ -92,7 +92,7 @@
 }
 
 #[derive(LintDiagnostic)]
-#[diag(mir_build_unsafe_op_in_unsafe_fn_union_field_requires_unsafe)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_union_field_requires_unsafe, code = E0133)]
 #[note]
 pub struct UnsafeOpInUnsafeFnAccessToUnionFieldRequiresUnsafe {
     #[label]
@@ -102,7 +102,10 @@
 }
 
 #[derive(LintDiagnostic)]
-#[diag(mir_build_unsafe_op_in_unsafe_fn_mutation_of_layout_constrained_field_requires_unsafe)]
+#[diag(
+    mir_build_unsafe_op_in_unsafe_fn_mutation_of_layout_constrained_field_requires_unsafe,
+    code = E0133
+)]
 #[note]
 pub struct UnsafeOpInUnsafeFnMutationOfLayoutConstrainedFieldRequiresUnsafe {
     #[label]
@@ -112,7 +115,10 @@
 }
 
 #[derive(LintDiagnostic)]
-#[diag(mir_build_unsafe_op_in_unsafe_fn_borrow_of_layout_constrained_field_requires_unsafe)]
+#[diag(
+    mir_build_unsafe_op_in_unsafe_fn_borrow_of_layout_constrained_field_requires_unsafe,
+    code = E0133,
+)]
 pub struct UnsafeOpInUnsafeFnBorrowOfLayoutConstrainedFieldRequiresUnsafe {
     #[label]
     pub span: Span,
@@ -121,7 +127,7 @@
 }
 
 #[derive(LintDiagnostic)]
-#[diag(mir_build_unsafe_op_in_unsafe_fn_call_to_fn_with_requires_unsafe)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_call_to_fn_with_requires_unsafe, code = E0133)]
 #[help]
 pub struct UnsafeOpInUnsafeFnCallToFunctionWithRequiresUnsafe {
     #[label]
diff --git a/tests/ui/pub/pub-reexport-priv-extern-crate.stderr b/tests/ui/pub/pub-reexport-priv-extern-crate.stderr
index c7fadc6..3fa5b0f 100644
--- a/tests/ui/pub/pub-reexport-priv-extern-crate.stderr
+++ b/tests/ui/pub/pub-reexport-priv-extern-crate.stderr
@@ -22,7 +22,7 @@
 LL |         extern crate core;
    |         ^^^^^^^^^^^^^^^^^^
 
-error: extern crate `core` is private, and cannot be re-exported (error E0365), consider declaring with `pub`
+error[E0365]: extern crate `core` is private, and cannot be re-exported, consider declaring with `pub`
   --> $DIR/pub-reexport-priv-extern-crate.rs:2:9
    |
 LL | pub use core as reexported_core;
@@ -34,4 +34,5 @@
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0603`.
+Some errors have detailed explanations: E0365, E0603.
+For more information about an error, try `rustc --explain E0365`.
diff --git a/tests/ui/rfcs/rfc-2396-target_feature-11/safe-calls.stderr b/tests/ui/rfcs/rfc-2396-target_feature-11/safe-calls.stderr
index aa660db..537819a 100644
--- a/tests/ui/rfcs/rfc-2396-target_feature-11/safe-calls.stderr
+++ b/tests/ui/rfcs/rfc-2396-target_feature-11/safe-calls.stderr
@@ -91,7 +91,7 @@
    = help: in order for the call to be safe, the context requires the following additional target features: sse2 and fxsr
    = note: the fxsr and sse2 target features being enabled in the build configuration does not remove the requirement to list them in `#[target_feature]`
 
-error: call to function `sse2` with `#[target_feature]` is unsafe and requires unsafe block (error E0133)
+error[E0133]: call to function `sse2` with `#[target_feature]` is unsafe and requires unsafe block
   --> $DIR/safe-calls.rs:70:5
    |
 LL |     sse2();
diff --git a/tests/ui/unsafe/edition-2024-unsafe_op_in_unsafe_fn.stderr b/tests/ui/unsafe/edition-2024-unsafe_op_in_unsafe_fn.stderr
index 2eb1754..fe12dd7 100644
--- a/tests/ui/unsafe/edition-2024-unsafe_op_in_unsafe_fn.stderr
+++ b/tests/ui/unsafe/edition-2024-unsafe_op_in_unsafe_fn.stderr
@@ -1,4 +1,4 @@
-warning: call to unsafe function `unsf` is unsafe and requires unsafe block (error E0133)
+warning[E0133]: call to unsafe function `unsf` is unsafe and requires unsafe block
   --> $DIR/edition-2024-unsafe_op_in_unsafe_fn.rs:10:5
    |
 LL |     unsf();
@@ -15,3 +15,4 @@
 
 warning: 1 warning emitted
 
+For more information about this error, try `rustc --explain E0133`.
diff --git a/tests/ui/unsafe/unsafe_op_in_unsafe_fn/edition_2024_default.stderr b/tests/ui/unsafe/unsafe_op_in_unsafe_fn/edition_2024_default.stderr
index e6d1d4e..05f36ab 100644
--- a/tests/ui/unsafe/unsafe_op_in_unsafe_fn/edition_2024_default.stderr
+++ b/tests/ui/unsafe/unsafe_op_in_unsafe_fn/edition_2024_default.stderr
@@ -1,4 +1,4 @@
-warning: call to unsafe function `unsf` is unsafe and requires unsafe block (error E0133)
+warning[E0133]: call to unsafe function `unsf` is unsafe and requires unsafe block
   --> $DIR/edition_2024_default.rs:13:5
    |
 LL |     unsf();
@@ -15,3 +15,4 @@
 
 warning: 1 warning emitted
 
+For more information about this error, try `rustc --explain E0133`.
diff --git a/tests/ui/unsafe/unsafe_op_in_unsafe_fn/in_2024_compatibility.stderr b/tests/ui/unsafe/unsafe_op_in_unsafe_fn/in_2024_compatibility.stderr
index 5092c1e..3f97199 100644
--- a/tests/ui/unsafe/unsafe_op_in_unsafe_fn/in_2024_compatibility.stderr
+++ b/tests/ui/unsafe/unsafe_op_in_unsafe_fn/in_2024_compatibility.stderr
@@ -1,4 +1,4 @@
-error: call to unsafe function `unsf` is unsafe and requires unsafe block (error E0133)
+error[E0133]: call to unsafe function `unsf` is unsafe and requires unsafe block
   --> $DIR/in_2024_compatibility.rs:7:5
    |
 LL |     unsf();
@@ -20,3 +20,4 @@
 
 error: aborting due to 1 previous error
 
+For more information about this error, try `rustc --explain E0133`.
diff --git a/tests/ui/unsafe/unsafe_op_in_unsafe_fn/rfc-2585-unsafe_op_in_unsafe_fn.stderr b/tests/ui/unsafe/unsafe_op_in_unsafe_fn/rfc-2585-unsafe_op_in_unsafe_fn.stderr
index 4bc604a1..1f80342 100644
--- a/tests/ui/unsafe/unsafe_op_in_unsafe_fn/rfc-2585-unsafe_op_in_unsafe_fn.stderr
+++ b/tests/ui/unsafe/unsafe_op_in_unsafe_fn/rfc-2585-unsafe_op_in_unsafe_fn.stderr
@@ -1,4 +1,4 @@
-error: call to unsafe function `unsf` is unsafe and requires unsafe block (error E0133)
+error[E0133]: call to unsafe function `unsf` is unsafe and requires unsafe block
   --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:9:5
    |
 LL |     unsf();
@@ -17,7 +17,7 @@
 LL | #![deny(unsafe_op_in_unsafe_fn)]
    |         ^^^^^^^^^^^^^^^^^^^^^^
 
-error: dereference of raw pointer is unsafe and requires unsafe block (error E0133)
+error[E0133]: dereference of raw pointer is unsafe and requires unsafe block
   --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:11:5
    |
 LL |     *PTR;
@@ -26,7 +26,7 @@
    = note: for more information, see issue #71668 <https://github.com/rust-lang/rust/issues/71668>
    = note: raw pointers may be null, dangling or unaligned; they can violate aliasing rules and cause data races: all of these are undefined behavior
 
-error: use of mutable static is unsafe and requires unsafe block (error E0133)
+error[E0133]: use of mutable static is unsafe and requires unsafe block
   --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:13:5
    |
 LL |     VOID = ();
@@ -47,7 +47,7 @@
 LL | #![deny(unused_unsafe)]
    |         ^^^^^^^^^^^^^
 
-error: call to unsafe function `unsf` is unsafe and requires unsafe block (error E0133)
+error[E0133]: call to unsafe function `unsf` is unsafe and requires unsafe block
   --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:24:5
    |
 LL |     unsf();
@@ -67,7 +67,7 @@
    |        ^^^^^^^^
    = note: `#[deny(unsafe_op_in_unsafe_fn)]` implied by `#[deny(warnings)]`
 
-error: dereference of raw pointer is unsafe and requires unsafe block (error E0133)
+error[E0133]: dereference of raw pointer is unsafe and requires unsafe block
   --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:26:5
    |
 LL |     *PTR;
@@ -76,7 +76,7 @@
    = note: for more information, see issue #71668 <https://github.com/rust-lang/rust/issues/71668>
    = note: raw pointers may be null, dangling or unaligned; they can violate aliasing rules and cause data races: all of these are undefined behavior
 
-error: use of mutable static is unsafe and requires unsafe block (error E0133)
+error[E0133]: use of mutable static is unsafe and requires unsafe block
   --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:28:5
    |
 LL |     VOID = ();
diff --git a/tests/ui/unsafe/unsafe_op_in_unsafe_fn/wrapping-unsafe-block-sugg.stderr b/tests/ui/unsafe/unsafe_op_in_unsafe_fn/wrapping-unsafe-block-sugg.stderr
index b9f5969..1ce22ec 100644
--- a/tests/ui/unsafe/unsafe_op_in_unsafe_fn/wrapping-unsafe-block-sugg.stderr
+++ b/tests/ui/unsafe/unsafe_op_in_unsafe_fn/wrapping-unsafe-block-sugg.stderr
@@ -1,4 +1,4 @@
-error: call to unsafe function `unsf` is unsafe and requires unsafe block (error E0133)
+error[E0133]: call to unsafe function `unsf` is unsafe and requires unsafe block
   --> $DIR/wrapping-unsafe-block-sugg.rs:13:5
    |
 LL |     unsf();
@@ -17,7 +17,7 @@
 LL | #![deny(unsafe_op_in_unsafe_fn)]
    |         ^^^^^^^^^^^^^^^^^^^^^^
 
-error: call to unsafe function `unsf` is unsafe and requires unsafe block (error E0133)
+error[E0133]: call to unsafe function `unsf` is unsafe and requires unsafe block
   --> $DIR/wrapping-unsafe-block-sugg.rs:17:5
    |
 LL |     unsf();
@@ -26,7 +26,7 @@
    = note: for more information, see issue #71668 <https://github.com/rust-lang/rust/issues/71668>
    = note: consult the function's documentation for information on how to avoid undefined behavior
 
-error: dereference of raw pointer is unsafe and requires unsafe block (error E0133)
+error[E0133]: dereference of raw pointer is unsafe and requires unsafe block
   --> $DIR/wrapping-unsafe-block-sugg.rs:25:13
    |
 LL |     let y = *x;
@@ -40,7 +40,7 @@
 LL | pub unsafe fn bar(x: *const i32) -> i32 {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: dereference of raw pointer is unsafe and requires unsafe block (error E0133)
+error[E0133]: dereference of raw pointer is unsafe and requires unsafe block
   --> $DIR/wrapping-unsafe-block-sugg.rs:29:9
    |
 LL |     y + *x
@@ -49,7 +49,7 @@
    = note: for more information, see issue #71668 <https://github.com/rust-lang/rust/issues/71668>
    = note: raw pointers may be null, dangling or unaligned; they can violate aliasing rules and cause data races: all of these are undefined behavior
 
-error: use of mutable static is unsafe and requires unsafe block (error E0133)
+error[E0133]: use of mutable static is unsafe and requires unsafe block
   --> $DIR/wrapping-unsafe-block-sugg.rs:38:13
    |
 LL |     let y = BAZ;
@@ -63,7 +63,7 @@
 LL | pub unsafe fn baz() -> i32 {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: use of mutable static is unsafe and requires unsafe block (error E0133)
+error[E0133]: use of mutable static is unsafe and requires unsafe block
   --> $DIR/wrapping-unsafe-block-sugg.rs:42:9
    |
 LL |     y + BAZ
@@ -72,7 +72,7 @@
    = note: for more information, see issue #71668 <https://github.com/rust-lang/rust/issues/71668>
    = note: mutable statics can be mutated by multiple threads: aliasing violations or data races will cause undefined behavior
 
-error: call to unsafe function `unsf` is unsafe and requires unsafe block (error E0133)
+error[E0133]: call to unsafe function `unsf` is unsafe and requires unsafe block
   --> $DIR/wrapping-unsafe-block-sugg.rs:48:36
    |
 LL | macro_rules! unsafe_macro { () => (unsf()) }
@@ -90,7 +90,7 @@
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: this error originates in the macro `unsafe_macro` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: call to unsafe function `unsf` is unsafe and requires unsafe block (error E0133)
+error[E0133]: call to unsafe function `unsf` is unsafe and requires unsafe block
   --> $DIR/wrapping-unsafe-block-sugg.rs:48:36
    |
 LL | macro_rules! unsafe_macro { () => (unsf()) }
@@ -105,3 +105,4 @@
 
 error: aborting due to 8 previous errors
 
+For more information about this error, try `rustc --explain E0133`.