Fixed: There is an exception when stopping livesync --watch - #1996

Will you share what the ugly exception is

^CTypeError: Cannot convert undefined or null to object
at LiveSyncService.Gaze.close (/Users/raikov/work/nativescript-cli/node_modules/gaze/lib/gaze.js:151:10)
at (/Users/raikov/work/nativescript-cli/lib/common/services/process-service.ts:26:21)
at arrayEach (/Users/raikov/work/nativescript-cli/node_modules/lodash/lodash.js:451:11)
at Function.forEach (/Users/raikov/work/nativescript-cli/node_modules/lodash/lodash.js:8634:14)
at ProcessService.executeAllCallbacks (/Users/raikov/work/nativescript-cli/lib/common/services/process-service.ts:25:4)
at process. (/Users/raikov/work/nativescript-cli/lib/common/services/process-service.ts:12:53)
at emitNone (events.js:86:13)
at process.emit (events.js:185:7)
at Signal.wrap.onsignal (internal/process.js:199:44)
/Users/raikov/work/nativescript-cli/node_modules/gaze/lib/gaze.js:151
Object.keys(self._watchers).forEach(function (file) {
^

TypeError: Cannot convert undefined or null to object
at LiveSyncService.Gaze.close (/Users/raikov/work/nativescript-cli/node_modules/gaze/lib/gaze.js:151:10)
at /Users/raikov/work/nativescript-cli/lib/common/services/process-service.js:25:31
at arrayEach (/Users/raikov/work/nativescript-cli/node_modules/lodash/lodash.js:451:11)
at Function.forEach (/Users/raikov/work/nativescript-cli/node_modules/lodash/lodash.js:8634:14)
at ProcessService.executeAllCallbacks (/Users/raikov/work/nativescript-cli/lib/common/services/process-service.js:24:11)
at process. (/Users/raikov/work/nativescript-cli/lib/common/services/process-service.js:7:79)
at emitOne (events.js:101:20)
at process.emit (events.js:188:7)
at process.exit (internal/process.js:146:15)
at process. (/Users/raikov/work/nativescript-cli/lib/common/errors.js:65:13)
at emitOne (events.js:96:13)
at process.emit (events.js:188:7)
at process._fatalException (bootstrap_node.js:254:26)

I spent some time debugging this issue and I came to a conclusion that the ugly exception is caused because the process exit handler is executed 2 times. This happens because when you press Ctrl+C the process sends two signals and the handler is executed once for each signal. The first execution stops the gaze watcher, but the second one tries to stop it again which results in that exception. I would suggest you do something like

this.$processService.attachToProcessExitSignals(this, () => {
    if (gazeWatcher) {
        gazeWatcher.close();
        gazeWatcher = null;
    }
});

Well, another round of digging and the issue seems to be a bit simpler. Calling gazeWatcher.close without a closure destroys its context. So the close method can't do its job.

👍

Even better 👍