fix(chunker): Don't underflow with wrong size_hint

[aawsome]

see #377

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 42.2%. Comparing base (667e9fb) to head (211573e).
Report is 1 commits behind head on main.

Additional details and impacted files

Files with missing lines	Coverage Δ
crates/core/src/chunker.rs	51.7% <100.0%> (+0.5%)	⬆️

... and 27 files with indirect coverage changes

[nardoor]

👍