message: Don't blow up if there are no session extension settings available.
diff: @@ -239,7 +239,7 @@ export class TerminalProxy implements ExtensionApi.Terminal {
  this.environment = new ProxyTerminalEnvironment(this._terminal);
  this._sessionConfiguration = _.cloneDeep(this._terminal.getSessionConfiguration());
  - this._sessionConfigurationExtensions = this._sessionConfiguration.extensions;
  + this._sessionConfigurationExtensions = this._sessionConfiguration.extensions ?? {};
  this._sessionConfiguration.extensions = null;
  }
  