This test checks that we surface the error for unexpected godebug values.

TODO(golang/go#67623): the diagnostic should be on the bad godebug value.

-- flags --
-min_go_command=go1.23
-errors_ok

-- go.mod --
module example.com/m //@diag("module", re`unknown godebug "panicnull"`)

go 1.23

godebug (
	panicnull=0 // misspelled
)
godebug panicnil=1
