AgvController cannot be started after being stopped

[sloebrich]

Describe the bug
When an AgvController is stopped and then started again, the application throws an error. This also happens if we wait a while between stop and start.

Is this a regression?
Afaik not

To Reproduce
With an mqtt broker running on localhost:1883, run the following script:

import { VirtualAgvAdapterOptions } from './../dist/adapter/virtual-agv-adapter.d';
import { AgvId } from './../dist/common/client-types.d';
import { ClientOptions } from './../dist/common/client.d';
import { VirtualAgvAdapter } from './adapter/virtual-agv-adapter';
import { AgvController } from './controller/agv-controller';

(async () => {
    // Use minimal client options: communication namespace and broker endpoint address.
    const agvClientOptions: ClientOptions = { interfaceName: "logctx42", transport: { brokerUrl: "mqtt://localhost:1883" }, vdaVersion: "2.0.0" };

    // The target AGV.
    const agvId001: AgvId = { manufacturer: "RobotCompany", serialNumber: "001" };

    // Specify associated adapter type; use defaults for all other AGV controller options. 
    const agvControllerOptions = {
        agvAdapterType: VirtualAgvAdapter,
    };

    // Use defaults for all adapter options of Virtual AGV adapter.
    const agvAdapterOptions: VirtualAgvAdapterOptions = {};

    // Create instance of AGV Controller with client, controller, and adapter options.
    const agvController = new AgvController(agvId001, agvClientOptions, agvControllerOptions, agvAdapterOptions);

    const sleep = async t => {await new Promise(r => setTimeout(r, 1000 * t))}
    await agvController.start();
    await sleep(5)
    await agvController.stop();
    await sleep(5)
    await agvController.start();
})()

Expected behavior
The AgvController restarts without throwing an error.

Screenshots

C:\Repositories\vda-5050-lib.js\src\common\client.ts:712
            throw new Error("Client is not started");
                  ^
Error: Client is not started
    at AgvController.publishTopic (C:\Repositories\vda-5050-lib.js\src\common\client.ts:712:19)
    at AgvController.publish (C:\Repositories\vda-5050-lib.js\src\client\agv-client.ts:63:21)
    at AgvController._publishCurrentState (C:\Repositories\vda-5050-lib.js\src\controller\agv-controller.ts:1216:43)
    at AgvController._connectionStateChangeCallback (C:\Repositories\vda-5050-lib.js\src\controller\agv-controller.ts:1178:22)
    at AgvController._emitConnectionStateChange (C:\Repositories\vda-5050-lib.js\src\common\client.ts:1186:18)
    at MqttClient.<anonymous> (C:\Repositories\vda-5050-lib.js\src\common\client.ts:1130:26)
    at MqttClient.emit (node:events:526:35)
    at MqttClient.emit (node:domain:488:12)
    at Readable.<anonymous> (C:\Repositories\vda-5050-lib.js\node_modules\mqtt\lib\client.js:1857:14)
    at Readable.emit (node:events:514:28)

Your Environment (please complete the following information):

• Package Version: 1.4.0
• Node.js Version: 20.10.0
• OS: Windows 10

Additional context
When the mqtt client connects on the second start, a publish state is triggered:

this._emitConnectionStateChange("online");

in \src\common\client.ts l.1131.

However this._isStarted is only set to true after connecting the mqtt broker in \src\common\client.ts l.472, leading to the error in AgvController.publishTopic.

A possible solution would be to set this._isStarted to true when the mqtt client connects, but before it emits the connection state change:

mqtt
...
    .on("connect", () => {
            this._isStarted = true
            this._emitConnectionStateChange("online");
    })

in \src\common\client.ts ll.1129-1132.

[keryigit]

The same issue happens when the mqtt library reconnects on its own. The suggested solution should work on that as well.