Auto merge of #18603 - tigercosmos:allocating, r=KiChjang

fix #18594: Unnecessarily allocating an error string

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r? @asajeffrey

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #18594 (github issue number if applicable).

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