code-dot-org/blockly-core — pull request #76 by Bjvanminnen (2014-05-06 18:28:49+00:00)
Title: [Finishes #70778304] null deref recycling toolbox block with running solution

Found via new relic.

Repro'd intermittently by dragging a block from the toolbox to the recycle icon while a program was running. Complete fix will involve also disabling the toolbox while program is running (something we only do right now in step mode).