When a job fails, which is run from SSIS Catalogue, then the error message is basically "look in SSIS Catalogue", which is not very useful. I suggest using the error message from the [SSISDB].[catalog].[event_messages] view instead for these cases.

In our home made monitoring system we're checking the subsystem in sysjobsteps, then use the command from there to identify the dtsx package name and looking up the latest message from [SSISDB].[catalog].[event_messages] for that package for the error message.