QuickBuild Server has hanged all running builds, when I've added a Resource that uses a script with error.

To reproduce:
Add a Resource that select all agents with following script evaluate to true:
   node.getAttribute(String.startWith("COACH_PFB_TA_HP"))

OR:
   node.getAttribute(\"COACH_PFB_TA_HP"\.*))

The error handling only showed for this Resource: "error on server" (in red), but under the hood all running builds has hanged, and new builds could not start (stayed on "Waiting").
Eventually we had to restart QB Server, loosing the queue of running and scheduled builds.