How to know that flowable throws exception in flow

I am using the flowable and wanted to know how flowable gives or how we know the flowable giving an error or exception. I am running the flowable docker image, so on the terminal, we come to know that exception occurs, but flowable UI does not show any message or inform that exception occurred.

You can frequently gain some information from the failed rest call in your browsers dev tools. If you are writing your own frontend, you could choose to log or display the error message.