message: fix: suppress chat state msg for unknown sender
diff: @@ -110,6 +110,11 @@ export default class ChatStatePlugin extends AbstractPlugin {
  private onComposing(from: JID) {
  let contact = this.pluginAPI.getContact(from);
  +
  + if (!contact) {
  + return;
  + }
  +
  let chatWindow = contact.getChatWindowController();
  //@TODO this doesn't work in all tabs
  @@ -118,6 +123,11 @@ export default class ChatStatePlugin extends AbstractPlugin {
  private onPaused(from: JID) {
  let contact = this.pluginAPI.getContact(from);
  +
  + if (!contact) {
  + return;
  + }
  +
  let chatWindow = contact.getChatWindowController();
  chatWindow.setBarText('');
  