message: Disable leave room button if user isn't in the room e.g peeking
diff: @@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
  limitations under the License.
  */
  -import React from 'react';
  +import React, { ContextType } from 'react';
  import { _t } from "../../../../../languageHandler";
  import RoomProfileSettings from "../../../room_settings/RoomProfileSettings";
  import AccessibleButton from "../../../elements/AccessibleButton";
  @@ -38,9 +38,10 @@ interface IState {
  @replaceableComponent("views.settings.tabs.room.GeneralRoomSettingsTab")
  export default class GeneralRoomSettingsTab extends React.Component<IProps, IState> {
  public static contextType = MatrixClientContext;
  + context: ContextType<typeof MatrixClientContext>;
  - constructor(props: IProps) {
  - super(props);
  + constructor(props: IProps, context: ContextType<typeof MatrixClientContext>) {
  + super(props, context);
  this.state = {
  isRoomPublished: false, // loaded async
  @@ -111,7 +112,11 @@ export default class GeneralRoomSettingsTab extends React.Component<IProps, ISta
  <span className='mx_SettingsTab_subheading'>{ _t("Leave room") }</span>
  <div className='mx_SettingsTab_section'>
  - <AccessibleButton kind='danger' onClick={this.onLeaveClick}>
  + <AccessibleButton
  + kind='danger'
  + onClick={this.onLeaveClick}
  + disabled={room.getMyMembership() !== "join"}
  + >
  { _t('Leave room') }
  </AccessibleButton>
  </div>
  