• Some of trigger functions (newer ones) have char **error argument and pass error messages back to frontend, some of them don't.

• Some of trigger functions become not supported in case of any error, some (most recent) try to stay supported and return special error code instead in case of temporary errors.

• Some trigger functions report a specific error message if they failed to get data from value cache, some of them don't.

It would be good to make error messages, error logging and becoming not supported more consistent across the whole range of supported trigger functions.