sentry/static/app/stores/types.tsx

/**
 * All stores implementing this interface have a common getState which returns
 * the stores state.
 *
 * When a store implements this it becomes usable with the `useLegacyStore` hook.
 *
 * Does not have the `[key: string]: any;` index signature that `Reflux.StoreDefinition` has.
 */
export interface StrictStoreDefinition<T> {
  /**
   * Returns the current state represented within the store
   */
  getState(): Readonly<T>;
  init(): void;
  state: Readonly<T>;
  /**
   * Trigger is not defined by the store definition, but is added by Reflux
   * We could try to type this better, but would need to update all .listen calls
   */
  trigger?: any;
}