feat(integrations): Add unraisable exception integration

[alexander-alderman-webb]

Closes #374

Adds an uncaught exception integration, enabled by default. The integration forwards the exception to Sentry only if the exception value and stacktrace are set.

The implementation and tests are adapted from excepthook. Sets sys.unraisablehook instead ofsys.excepthook, and changes relevant signatures and types. Compared with the excepthook integration, there is no always_run parameter. As far as I can tell the option was added to avoid excessive errors in interactive shells, which does not apply to unraisable errors.

Unlike in the excepthook tests, the unraisablehook test does not check for the presence of the local variable in the pre-context. The local variable from the excepthook test is not captured in an analogous test with an unraisable exception because an (unraisable) exception in __del__ has a stack frame with only one level.

A good source about unraisable exceptions: https://vstinner.github.io/sys-unraisablehook-python38.html

[codecov]

Codecov Report

❌ Patch coverage is 85.71429% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.89%. Comparing base (b1a8b63) to head (2f2fef5).
⚠️ Report is 7 commits behind head on master.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
sentry_sdk/integrations/unraisablehook.py	85.71%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4733      +/-   ##
==========================================
- Coverage   84.92%   84.89%   -0.03%     
==========================================
  Files         156      157       +1     
  Lines       16115    16136      +21     
  Branches     2741     2744       +3     
==========================================
+ Hits        13685    13698      +13     
- Misses       1643     1651       +8     
  Partials      787      787              

Files with missing lines	Coverage Δ
sentry_sdk/integrations/unraisablehook.py	85.71% <85.71%> (ø)

... and 5 files with indirect coverage changes

[sentrivana]

The integration looks good 💪🏻 Left two comments, please have a look

[sentrivana]

I'd not make this default just yet, let's give it some time to soak. We can turn it on by default in 3.0 on the potel-base branch -- could you prepare a PR for that?

[alexander-alderman-webb]

yes sounds good! #4749

[sentrivana]

Why do we need to test this both with and without HTTP/2? Is the behavior of the integration any different?

[alexander-alderman-webb]

No, this is copied over from test_excepthook. I guess the test is more of an integration test as it checks that the unraisable exception goes all the way to the transport.

I'm happy to change this. Would you just use Http2Transport now that will be the default?

[sentrivana]

Didn't realize we're doing the same in the excepthook tests. I guess fine to keep as is then.

[sentrivana]

🚀