lib/model: Let fakeConnection call Model.Closed on close (#5682)

lib/model/model.go

@@ -1383,10 +1383,12 @@ func (m *model) Closed(conn protocol.Connection, err error) {
 	device := conn.ID()
 
 	m.pmut.Lock()
+	defer m.pmut.Unlock()
 	conn, ok := m.conn[device]
-	if ok {
-		m.progressEmitter.temporaryIndexUnsubscribe(conn)
+	if !ok {
+		return
 	}
+	m.progressEmitter.temporaryIndexUnsubscribe(conn)
 	delete(m.conn, device)
 	delete(m.connRequestLimiters, device)
 	delete(m.helloMessages, device)
@@ -1394,7 +1396,6 @@ func (m *model) Closed(conn protocol.Connection, err error) {
 	delete(m.remotePausedFolders, device)
 	closed := m.closed[device]
 	delete(m.closed, device)
-	m.pmut.Unlock()
 
 	l.Infof("Connection to %s at %s closed: %v", device, conn.Name(), err)
 	events.Default.Log(events.DeviceDisconnected, map[string]string{