Bugfix, studio report by Pablo Venomgfx

- insert key crashed when object ipo was in action, but action got unlinked
  from object

source/blender/src/keyframing.c

@@ -1347,7 +1347,8 @@ static void commonkey_context_getv3d (ListBase *sources, bKeyingContext **ksc)
 						if (achan && achan->ipo)
 							cks->ipo= achan->ipo;
 					}
-					
+					/* cks->ipo can be NULL while editing */
+					if(cks->ipo) {
 						/* deselect all ipo-curves */
 						for (icu= cks->ipo->curve.first; icu; icu= icu->next) {
 							icu->flag &= ~IPO_SELECT;
@@ -1356,6 +1357,7 @@ static void commonkey_context_getv3d (ListBase *sources, bKeyingContext **ksc)
 				}
 			}
 		}
+	}
 }
 
 /* helper for commonkey_context_get() -  get keyingsets for buttons window */