fix: do not show error from preview initialization when stop is called

When preview is called with webpack from Public API, if you stop the livesync (via stopLiveSync method) while webpack is still working, in the output you'll see an error as webpack's child process exits with `null` exit code.
However, this error does not have any meaning for the user, so we shouldn't raise it.
Move the logging of the error to LiveSyncService's handler of `previewAppLiveSyncError` event - in the described case it will not be raised as LiveSyncService had already removed all listeners.

Author: rosen-vladimirov

lib/services/livesync/livesync-service.ts

@@ -140,6 +140,7 @@ export class LiveSyncService extends EventEmitter implements IDebugLiveSyncServi
 	@cache()
 	private attachToPreviewAppLiveSyncError(): void {
 		this.$previewAppLiveSyncService.on(LiveSyncEvents.previewAppLiveSyncError, liveSyncData => {
+			this.$logger.error(liveSyncData.error);
 			this.emit(LiveSyncEvents.previewAppLiveSyncError, liveSyncData);
 		});
 	}

lib/services/livesync/playground/preview-app-livesync-service.ts

@@ -43,7 +43,7 @@ export class PreviewAppLiveSyncService extends EventEmitter implements IPreviewA
 					this.deviceInitializationPromise[device.id] = null;
 				}
 			} catch (error) {
-				this.$logger.error(error);
+				this.$logger.trace(`Error while sending files on device ${device && device.id}. Error is`, error);
 				this.emit(PreviewAppLiveSyncEvents.PREVIEW_APP_LIVE_SYNC_ERROR, {
 					error,
 					data,