Add two words to clarify

Author: RandomSort

docs/error-handling.md

@@ -118,7 +118,7 @@ The public error API
   Otherwise this should return a `git_error` object indicating the class
   of error and the error message that was generated by the library.
   Do not use this function unless the prior call to a libgit2 API
-  returned an error, as it can give misleading results.
+  returned an error, as it can otherwise give misleading results.
   libgit2's error strings are not cleared aggressively, 
   and this function may return an error string that reflects a prior error,
   possibly even reflecting internal state.

include/git2/errors.h

@@ -113,7 +113,7 @@ typedef enum {
  *
  * The default behaviour of this function is to return NULL if no previous error has occurred.
  * However, libgit2's error strings are not cleared aggressively, so a prior
- * (unrelated) error may be returned. This can avoided by only calling
+ * (unrelated) error may be returned. This can be avoided by only calling
  * this function if the prior call to a libgit2 API returned an error.
  *
  * @return A git_error object.