Requires full error message in assert helpers.
Some of the error messages we asset on add a native javascript stack
trace, which would be a pain to add to the messages and maintain. This
PR allows you to just add `\n in <stack>` placeholder to the error
message to denote a native stack trace is present in the message.
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Note: i vibe coded this so it was a pain to backtrack this to break this
into a stack, I tried and gave up, sorry.
3e1abcc8d7