Bugfix [#33268] Crash when delete all or segment from curve with SplineIK

Path rebuild may fail after certain editing operations. Instead of blindly
assuming that path rebuilds will always succeed, we now give up trying to
evaluate in case of failure.

source/blender/blenkernel/intern/armature.c

@@ -1822,8 +1822,15 @@ static void splineik_init_tree_from_pchan(Scene *scene, Object *UNUSED(ob), bPos
 		 */
 
 		/* only happens on reload file, but violates depsgraph still... fix! */
-		if ((cu->path == NULL) || (cu->path->data == NULL))
+		if (ELEM(NULL, cu->path, cu->path->data)) {
 			BKE_displist_make_curveTypes(scene, ikData->tar, 0);
+			
+			/* path building may fail in EditMode after removing verts [#33268]*/
+			if (ELEM(NULL, cu->path, cu->path->data)) {
+				/* BLI_assert(cu->path != NULL); */
+				return;
+			}
+		}
 	}
 
 	/* find the root bone and the chain of bones from the root to the tip