Fixes EventEmitter leak in AudioService related to _resetNoDataInterval

[chooper]

Fixes EventEmitter leak in AudioService related to _resetNoDataInterval

Summary

Fixes an EventEmitter leak in AudioService by preventing the _resetNoDataInterval callback from being registered multiple times.

Motivation

In my current setup, silence detection kicks in to restart the mic instance periodically. This has been fine for my use case; however, after a small number of those, I get warnings about an EventEmitter leak.

note: for testing, I set NO_DATA_INTERVAL_SEC to 1 and set inputDevice in the config to something that didn't exist

$ node --trace-warnings index.js --debug
...
Aug-18-2022 21:54:10 alert : No Mic Data for 1 Seconds
Aug-18-2022 21:54:10 warning : Restarting mic instance
Aug-18-2022 21:54:10 alert : Mic Instance Has STOPPED
Aug-18-2022 21:54:10 info : Mic Instance Has Started
(node:9976) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 data listeners added to [IsSilence]. Use emitter.setMaxListeners() to increase limit
    at _addListener (events.js:389:17)
    at IsSilence.addListener (events.js:405:10)
    at IsSilence.Readable.on (_stream_readable.js:873:35)
    at AudioService.onData (/home/pi/src/fd-tone-notify/service/AudioService.js:55:30)
    at AudioService.listenForMicInputEvents (/home/pi/src/fd-tone-notify/service/AudioService.js:63:14)
    at AudioService.restart (/home/pi/src/fd-tone-notify/service/AudioService.js:25:14)
    at Timeout._onTimeout (/home/pi/src/fd-tone-notify/service/AudioService.js:49:22)
    at listOnTimeout (internal/timers.js:554:17)
    at processTimers (internal/timers.js:497:7)

Description of problem

In the AudioService class, when a data event hasn't been emitted for NO_DATA_INTERVAL_SEC seconds, AudioService.restart() is invoked.

In the #restart method, the following two lines interact to result in the emitter leak:

        this._rebindDataListenerCallbacks();
        this.listenForMicInputEvents();

In #_rebindDataListenerCallbacks, all callbacks that were registered using the AudioService.onData method are re-applied to the (new) mic instance. More specifically, the callbacks are registered on the mic's audioStream (which is called IsSilence in the library code)

This by itself is fine, but in #listenForMicInputEvents the callback to reset the silence detection interval is registered using the onData method, resulting it in getting re-added to the persistent callback list.

This means that if restart is called for the 10th time, the resetNoDataInterval callback will be re-registered ten times on that turn.

Explanation of solution

Rather than adding #_resetNoDataInterval to a persistent list of callbacks to be re-registered every restart, this PR instead leaves the callback out of the list and instead registers it directly with the mic's audioStream component.

[chooper]

Keeping as a draft while I do more testing.

[chooper]

I've been running this branch successfully since the 21st with ~40 tone detection events without any restarts. This is ready for review.

[kdolan]

Looks good.