Crash at empty default export #4670

[denbezrukov]

Summary

Fix #4670

Test Plan

cargo test

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[github-actions]

Parser conformance results on ubuntu-latest

js/262

Test result	main count	This PR count	Difference
Total	48863	48863	0
Passed	47810	47810	0
Failed	1053	1053	0
Panics	0	0	0
Coverage	97.84%	97.84%	0.00%

jsx/babel

Test result	main count	This PR count	Difference
Total	40	40	0
Passed	37	37	0
Failed	3	3	0
Panics	0	0	0
Coverage	92.50%	92.50%	0.00%

symbols/microsoft

Test result	main count	This PR count	Difference
Total	6212	6212	0
Passed	1764	1764	0
Failed	4448	4448	0
Panics	0	0	0
Coverage	28.40%	28.40%	0.00%

ts/babel

Test result	main count	This PR count	Difference
Total	639	639	0
Passed	573	573	0
Failed	66	66	0
Panics	0	0	0
Coverage	89.67%	89.67%	0.00%

ts/microsoft

Test result	main count	This PR count	Difference
Total	17224	17224	0
Passed	13121	13121	0
Failed	4103	4103	0
Panics	0	0	0
Coverage	76.18%	76.18%	0.00%