Fix connection errors when replacing node

- Avoid connecting the signals to nonexistent methods
- Preserve only persistent connections

scene/main/node.cpp

@@ -2498,9 +2498,12 @@ void Node::_replace_connections_target(Node *p_new_target) {
 
 		Connection &c = E->get();
 
+		if (c.flags & CONNECT_PERSIST) {
 			c.source->disconnect(c.signal, this, c.method);
+			ERR_CONTINUE(!p_new_target->has_method(c.method));
 			c.source->connect(c.signal, p_new_target, c.method, c.binds, c.flags);
 		}
+	}
 }
 
 Vector<Variant> Node::make_binds(VARIANT_ARG_DECLARE) {