Probably a similar story since the [assert](https://searchfox.org/mozilla-central/rev/6f0792f9f3f1a6175ce1f8e318a8a0f51ba76dee/js/src/builtin/String.cpp#582) would be gone. Seems `gcc`-based build is more picky about these kinds of issues.
Bug 1863131 Comment 3 Edit History
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Probably a similar story since the [assert](https://searchfox.org/mozilla-central/rev/6f0792f9f3f1a6175ce1f8e318a8a0f51ba76dee/js/src/builtin/String.cpp#582) would be gone in opt builds Seems `gcc`-based build is more picky about these kinds of issues.