Warnings in GCC and VC

[Thrameos]

This PR deals with warnings that are currently triggering in VC and GCC.

• Local variables not used on exception catches
• Mismatched types between primitives requiring casts
• A throw path on extern "C" that must not be allowed to propagate or it will trigger a segfault.

[codecov[bot]]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (4471a27) 87.49% compared to head (9d5d399) 87.44%.

Files	Patch %	Lines
native/common/jp_proxy.cpp	0.00%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1161 +/- ## ========================================== - Coverage 87.49% 87.44% -0.05% ========================================== Files 113 113 Lines 10233 10236 +3 Branches 4057 4057 ========================================== - Hits 8953 8951 -2 - Misses 688 692 +4 - Partials 592 593 +1 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.