Denial of Service in mruby due to null pointer dereference

The following file causes a segmentation fault in mruby, which also causes a segmentation fault in mruby-engine. I've minimized this file down to the bare bones what crashes it, and renamed variables so you can see what is needed and what isn't.

a=*"any splat operator", case "any object or nil"
when "any value"
  redo |b|
  "any return object"
end