Hi @dotnet/mono-team, it looks like the changes introduced in 5236bb8 are causing a number of tests to fail on wasm only. I've been able to narrow down the failures to a single unit test in fe3a627. The failure happens deterministically and only occurs on wasm targets. It appears to occur because the JsonDocument._utf8Json span is reported as empty, even though my changes in the second commit make this case impossible -- I suspect this could be caused by some kind of memory corruption.

Originally posted by @eiriktsarpalis in #79890 (comment)

See https://github.com/dotnet/runtime/pull/79890/checks?check_run_id=10279234698 and https://dev.azure.com/dnceng-public/public/_build/results?buildId=119299&view=ms.vss-test-web.build-test-results-tab for more information.