Fix typo. Close SF Bug 606354.

Doc/lib/libcodecs.tex

@@ -100,7 +100,7 @@ also defines these utility functions:
 
 \begin{funcdesc}{register_error}{name, error_handler}
 Register the error handling function \var{error_handler} under the
-name \var{name}. \vari{error_handler} will be called during encoding
+name \var{name}. \var{error_handler} will be called during encoding
 and decoding in case of an error, when \var{name} is specified as the
 errors parameter. \var{error_handler} will be called with an
 \exception{UnicodeEncodeError}, \exception{UnicodeDecodeError} or