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Fix Cannot read property 'length' of undefined

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This error was reported by TrackJS various times:

```
TypeError: Cannot read property 'length' of undefined
  at EventEmitter.<anonymous> (file:///Users/jviotti/Projects/resin/etcher/lib/browser/app.js:104:15)
  at emitOne (events.js:77:13)
  at EventEmitter.emit (events.js:169:7)
  at /Users/jviotti/Projects/resin/etcher/lib/browser/modules/drive-scanner.js:131:17
  at processQueue (/Users/jviotti/Projects/resin/etcher/node_modules/angular/angular.js:15616:28)
  at /Users/jviotti/Projects/resin/etcher/node_modules/angular/angular.js:15632:27
  at Scope.$eval (/Users/jviotti/Projects/resin/etcher/node_modules/angular/angular.js:16884:28)
  at Scope.$digest (/Users/jviotti/Projects/resin/etcher/node_modules/angular/angular.js:16700:31)
  at /Users/jviotti/Projects/resin/etcher/node_modules/angular/angular.js:16923:26
  at completeOutstandingRequest (/Users/jviotti/Projects/resin/etcher/node_modules/angular/angular.js:5825:10),
```

The error refers to the following line in `app.js`:

```js
if (drives.length === 1 && self.selection.hasImage()) {
```

Which indicates that the array of detected drives returned to the main
controller is `undefined` for some reason.

The problem resides in the `.scan()` method of `DriveScannerService`:

```js
this.scan = function() {
  return $q.when(drives.listRemovable()).catch(dialog.showError);
};
```

When an error is thrown when scanning the drives, the `.catch()` block
is called. This means that the error is not propagated to the outer code
and the promise resolves with `undefined`.

The solution is to move `.catch()` to the place `.scan()` is called,
instead of making use of it in the low-level parts of the process.
This commit is contained in:
Juan Cruz Viotti 2016-03-17 09:36:43 -04:00
parent 78bb151387
commit fda6f8a6a5
1 changed files with 2 additions and 2 deletions
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4
lib/browser/modules/drive-scanner.js
View File

@ -100,7 +100,7 @@ driveScanner.service('DriveScannerService', function($q, $interval, $timeout) {
* });
*/
this.scan = function() {
return $q.when(drives.listRemovable()).catch(dialog.showError);
return $q.when(drives.listRemovable());
};
/**
@ -130,7 +130,7 @@ driveScanner.service('DriveScannerService', function($q, $interval, $timeout) {
return self.scan().then(function(drives) {
emitter.emit('scan', drives);
self.setDrives(drives);
});
}).catch(dialog.showError);
};
// Make sure any pending interval is cancelled