dictBuilder fails to create dictionary on certain input

Properly expressed with an error code (see zstd_errors.h)
and a cli return code != 0

lib/common/zstd_errors.h

@@ -57,6 +57,7 @@ typedef enum {
   ZSTD_error_maxSymbolValue_tooSmall,
   ZSTD_error_dictionary_corrupted,
   ZSTD_error_dictionary_wrong,
+  ZSTD_error_dictionaryCreation_failed,
   ZSTD_error_maxCode
 } ZSTD_ErrorCode;