modify the throw information exception

mindspore/ccsrc/minddata/dataset/api/datasets.cc

@@ -638,7 +638,6 @@ Status SchemaObj::Init() {
                                    "\"columns\" node is required in the schema json file.");
     } catch (const std::exception &err) {
       std::string err_msg = "Schema file failed to load: ";
-      err_msg += err.what();
       RETURN_STATUS_SYNTAX_ERROR(err_msg);
     }
     return from_json(js);

mindspore/ccsrc/minddata/dataset/api/text.cc

@@ -315,7 +315,7 @@ Status LookupOperation::ValidateParams() {
 
   default_id_ = vocab_->Lookup(unknown_token_);
   if (default_id_ == Vocab::kNoTokenExists) {
-    std::string err_msg = "Lookup: " + unknown_token_ + " doesn't exist in vocab.";
+    std::string err_msg = "Lookup: \"" + unknown_token_ + "\" doesn't exist in vocab.";
     MS_LOG(ERROR) << err_msg;
     RETURN_STATUS_SYNTAX_ERROR(err_msg);
   }