Add exception type to SomeException displayException; modify default handler
This is an alternative to !11737.
The primary differences are:
- Exception type data added to
SomeException
'sdisplayException
, rather than the handler. - Handler adding a header e.g.
Exception in thread ...
.
This is discussed at: https://github.com/haskell/core-libraries-committee/issues/261.
If the CLC proposal is approved I will make the prerequisite MRs fix tests in other repos (e.g. stm
).