Mixin conflict handling failing to skip nonrequired mixin

[someaddons]

The "required:false" flag in the mixin config
https://github.com/someaddons/mixindebug/blob/9bc8ad2f5a6394635580bbe339d72d452ae38cb7/src/main/resources/template.mixins.json#L2
does only work if mixin.debug=true is enabled, else two conflicting mixins will crash.

Here is a simple fabric template repo to reproduce it, launching it with vmArg '-Dmixin.debug=true' allows it to run skipping one of the conflicting mixins as it should, while commenting it out causes a crash.
https://github.com/someaddons/mixindebug