index: also sanity check entry size with compressed entries

We have a check in place whether the index has enough data left for the
required footer after reading an index entry, but this was only used for
uncompressed entries. Move the check down a bit so that it is executed
for both compressed and uncompressed index entries.
diff --git a/src/index.c b/src/index.c
index ed9f478..bff5d7f 100644
--- a/src/index.c
+++ b/src/index.c
@@ -2358,10 +2358,6 @@
 		}
 
 		entry_size = index_entry_size(path_length, 0, entry.flags);
-
-		if (INDEX_FOOTER_SIZE + entry_size > buffer_size)
-			return 0;
-
 		entry.path = (char *)path_ptr;
 	} else {
 		size_t varint_len;
@@ -2386,6 +2382,9 @@
 		entry.path = tmp_path;
 	}
 
+	if (INDEX_FOOTER_SIZE + entry_size > buffer_size)
+		return 0;
+
 	if (index_entry_dup(out, index, &entry) < 0) {
 		git__free(tmp_path);
 		return 0;