(BUG) SystemExits Not Thrown and Caught

[zhanwenchen]

Currently, most exceptions are generic Exceptions and are caught without reraising. This prohibits any fatal exceptions from cascading into a desired system exit. Instead, we want to catch and reraise fatal errors (SystemExits) independently from generic Exceptions like this:

From:

try:
    ...
except Exception as e:
    print(...)
    pass

To:

try:
    ...
except SystemExit as e:
    raise SystemExit('FATAL ERROR ...') from e
except Exception as e:
    print(...)
    pass

We also want to raise SystemExits from specific Exceptions (e.g., RuntimeError) for fatal errors.

[zhanwenchen]

Problem is that SystemExits are handled differently from other built-in Exceptions. It's truncated.

In the long term, we should only catch and raise repo-specific exceptions in most circumstances. Generic Exceptions still should not be caught.