bug#37480: 27.0.50; uncaught exception

[Eli Zaretskii]

> From: Christian Johansson <christian@cvj.se>
> Date: Sun, 22 Sep 2019 16:00:38 +0200
> 
> I want to handle errors occurring in asynchronous threads like in this
> example, is it possible?

For some value of "possible".  From the ELisp manual:

     When code run by a thread signals an error that is unhandled, the
  thread exits.  Other threads can access the error form which caused the
  thread to exit using the following function.

   -- Function: thread-last-error
       This function returns the last error form recorded when a thread
       exited due to an error.  Each thread that exits abnormally
       overwrites the form stored by the previous thread’s error with a
       new value, so only the last one can be accessed.

> (make-thread
> (lambda()
> (message "Start of asynchronous thread")
> (signal 'error '("Fatal error"))
> (message "End of asynchronous thread")))

I'm not sure I understand what you tried to accomplish with this code.
It doesn't seem to handle errors in any way.  Could you explain what
you are trying to do?