[Issue 18208] demangle RangeError at src/core/demangle.d(230)

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=18208

--- Comment #3 from Timothee Cour <timothee.cour2 at gmail.com> ---
https://github.com/dlang/druntime/pull/2116

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