avoid error when coro.cr_frame is None

[Zac-HD]

.cr_frame is set to None when a coroutine closes, per python/cpython#112428, and while this rarely comes up in practice you can probably guess why I'm opening a PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00000%. Comparing base (84fbcb7) to head (26f55f6).
⚠️ Report is 44 commits behind head on main.

Additional details and impacted files

@@               Coverage Diff               @@
##                 main        #3338   +/-   ##
===============================================
  Coverage   100.00000%   100.00000%           
===============================================
  Files             125          125           
  Lines           19586        19597   +11     
  Branches         1342         1343    +1     
===============================================
+ Hits            19586        19597   +11     

Files with missing lines	Coverage Δ
src/trio/_core/_run.py	100.00000% <100.00000%> (ø)
src/trio/_tests/test_tracing.py	100.00000% <100.00000%> (ø)

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[A5rocks]

Maybe this could be simpler? Makes sense to me.

Maybe @graingert since idk too much about this.

[A5rocks]

I would understand if the # pragma: no branch was for the gi_frame is None case... but then why isn't this covered?

EDIT: adding an assert False, this seems to get run. So I think the no cover isn't necessary.

Suggested change

	yield gi_frame, gi_frame.f_lineno # pragma: no cover
	yield gi_frame, gi_frame.f_lineno

[Zac-HD]

I think this is just a codecov bug 🤷