RFC: Change what assert does on error

[Richard Andrew Cattermole (Rikki)]

Hello!

I've managed to have a chat with Walter to discuss what assert 
does on error.

In recent months, it has become more apparent that our current 
error-handling behaviours have some serious issues. Recently, we 
had a case where an assert threw, killed a thread, but the 
process kept going on. This isn't what should happen when an 
assert fails.

An assert specifies that the condition must be true for program 
continuation. It is not for logic level issues, it is solely for 
program continuation conditions that must hold.

Should an assert fail, the most desirable behaviour for it to 
have is to print a backtrace if possible and then immediately 
kill the process.

What a couple of us are suggesting is that we change the default 
behaviour from ``throw AssertError``.
To: ``printBacktrace; exit(-1);``

There would be a function you can call to set it back to the old 
behaviour. It would not be permanent.

This is important for unittest runners, you will need to change 
to the old behaviour and back again (if you run the main function 
after).

Before any changes are made, Walter wants a consultation with the 
community to see what the impact of this change would be.

Does anyone have a case, implication, or scenario where this 
change would not be workable?

Destroy!