Add missing sao->isGone() checks

fixes #9883

src/collision.cpp

@@ -397,7 +397,8 @@ collisionMoveResult collisionMoveSimple(Environment *env, IGameDef *gamedef,
 				// we directly use the callback to populate the result to prevent
 				// a useless result loop here
 				auto include_obj_cb = [self, &objects] (ServerActiveObject *obj) {
-					if (!self || (self != obj && self != obj->getParent())) {
+					if (!obj->isGone() &&
+						(!self || (self != obj && self != obj->getParent()))) {
 						objects.push_back((ActiveObject *)obj);
 					}
 					return false;

src/serverenvironment.cpp

@@ -1623,6 +1623,8 @@ void ServerEnvironment::getSelectedActiveObjects(
 	const v3f line_vector = shootline_on_map.getVector();
 
 	for (auto obj : objs) {
+		if (obj->isGone())
+			continue;
 		aabb3f selection_box;
 		if (!obj->getSelectionBox(&selection_box))
 			continue;