OpenEye Report: http://openeye.openmods.info/crashes/87a261e5123407e39b8a0846bdeeadf3

To replicate:
pick block reinforced obsidian while in creative - client crash.

crash-2016-04-25_03.25.38-client.txt

PS: "Duplicate" as in already reported and handled ( #38 ), not as in "there's another issue for it".