Summary

This pull request resolves #1495 .

To test the behavior, you can modify retrieveWSSURL method as below plus run cd examples && ./link.sh && npm start to see how it works:

  private reconnecting: boolean = false;

  private async retrieveWSSURL(): Promise<AppsConnectionsOpenResponse> {
    if (this.reconnecting && this.numOfConsecutiveReconnectionFailures % 2 === 0) {
      const e: WebAPIPlatformError = {
        name: 'XXX',
        message: 'An API error occurred: XXX',
        code: APICallErrorCode.PlatformError,
        data: {
          ok: false,
          error: 'internal_error',
        },
      };
      throw e;
    }
    this.reconnecting = true;
    try {
      this.logger.debug('Going to retrieve a new WSS URL ...');
      return await this.webClient.apps.connections.open();
    } catch (error) {
      this.logger.error(`Failed to retrieve a new WSS URL for reconnection (error: ${error})`);
      throw error;
    }
  }

The direct cause of the reconnection failure was that there is no logic to handle connecting:reconnecting in the current code. When you use a sub state machine in this state machine library, it has a state hierarchy and your code needs to have the comprehensive set of handlers for all the state sets.

To prevent this type of coding error happening again in the future (actually, this pattern errors existed much more before 1.3.0 release), I've added enums for the sub state machines - ConnectingState and ConnectedState. With these, passing a state to a sub machine is type-safe. Passing the top-level State enum to a sub state machine does not compile anymore.

Requirements (place an x in each [ ])

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.