fix hang when parsing egregiously long integer

[davidhewitt]

As per the title 😄

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

:loudspeaker: Thoughts on this report? Let us know!

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #77 will not alter performance

_{Comparing dh/bigint-bailout (ef34498) with main (c31fc7d)}

Summary

✅ 59 untouched benchmarks