fix: preserve generator error context #13922

Job	Run time
Test mypyc suite with 32-bit Python	7m 2s
Test suite with py38-ubuntu, mypyc-compiled	18m 22s
Test suite with py38-windows-64	20m 10s
Test suite with py39-ubuntu	17m 28s
Test suite with py310-ubuntu	16m 39s
Test suite with py311-ubuntu, mypyc-compiled	16m 2s
Test suite with py312-ubuntu, mypyc-compiled	18m 28s
Test suite with py313-ubuntu, mypyc-compiled	18m 54s
mypyc runtime tests with py39-macos	6m 0s
Type check our own code (py38-ubuntu)	1m 51s
Type check our own code (py38-windows-64)	2m 19s
Formatting and code style with Black + ruff	55s
	2h 24m 10s

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