Fix for tree locking.

src/MATLAB/+Editor/TreeLockAction.m

@@ -6,6 +6,10 @@
 function historyAction = TreeLockAction(familyID)
     global CellFamilies
     
+    if ( isempty(CellFamilies(familyID).bLocked) )
+        CellFamilies(familyID).bLocked = 0;
+    end
+    
     bIsLocked = CellFamilies(familyID).bLocked;
     CellFamilies(familyID).bLocked = ~bIsLocked;