fix typo

errors.go

diff --git a/errors.go b/errors.go
index d73f3d1..3d515d8 100644
--- a/errors.go
+++ b/errors.go
@@ -61,7 +61,7 @@
 	"strings"
 )
 
-// stack represents a stack of programm counters.
+// stack represents a stack of program counters.
 type stack []uintptr
 
 func (s *stack) Stack() []uintptr { return *s }