Run like so:
$ ../tool/zjit_iongraph.rb ../build-dev/miniruby --zjit-call-threshold=2 tmp/ghbug.rb
false
false
tmp/ghbug.rb:3:in 'Object#doit': this shouldnt ever be nil (RuntimeError)
from tmp/ghbug.rb:10:in '<main>'
W, [2025-12-09T11:00:32.070382 #67400] WARN -- : Command failed with exit status 1
zjit_iongraph_67405.html
$
Then open zjit_iongraph_67405.html with your browser.