Scripted Interface affordances should have a uniform way to report script errors

[jimingham]

Script affordances can fail not just for expected reasons, but also unexpected ones like "the underlying script code failed to compile or got a runtime error". Debugging those failures can be tricky because these failures often happen in places where surfacing errors to the user is not straightforward.

So we should come up with some good scheme for reporting such errors when running scripted affordances.

[llvmbot]

@llvm/issue-subscribers-lldb

Author: None (jimingham)

Script affordances can fail not just for expected reasons, but also unexpected ones like "the underlying script code failed to compile or got a runtime error". Debugging those failures can be tricky because these failures often happen in places where surfacing errors to the user is not straightforward.

So we should come up with some good scheme for reporting such errors when running scripted affordances.