fix: update error types for upstream errors and JSON marshal failure

relay/compatible_handler.go

@@ -130,7 +130,7 @@ func TextHelper(c *gin.Context, info *relaycommon.RelayInfo) (newAPIError *types
 
 		jsonData, err := common.Marshal(convertedRequest)
 		if err != nil {
-			return types.NewError(err, types.ErrorCodeConvertRequestFailed, types.ErrOptionWithSkipRetry())
+			return types.NewError(err, types.ErrorCodeJsonMarshalFailed, types.ErrOptionWithSkipRetry())
 		}
 
 		// apply param override