title: Creating Sub-Collection in Document from Flutter app
body: <p>I am trying to create a sub-collection in a document and set data to documents in the created sub-collection. </p>
  
  <p>I have tried this but the program crashes every time I run this. </p>
  
  <pre><code>  await Firestore.instance
        .collection('/path')
        .document("documentPath")
        .collection('/subCollectionPath')
        .document()
        .setData({
      'TestData': "Data",
    }).then((onValue) {
      print('Created it in sub collection');
    }).catchError((e) {
      print('======Error======== ' + e);
    });
  </code></pre>
  
  <p>I have also looked online but I cannot find any documentation for it.</p>
  
  <p>Any ideas? </p>
  
  <p>When I try the above code, the app crashes with the following message </p>
  
  <pre><code>   flutter: EVENT StorageTaskEventType.success
     *** First throw call stack:
     (
      0   CoreFoundation                      0x0000000111eb61bb __exceptionPreprocess + 331
      1   libobjc.A.dylib                     0x0000000111454735 objc_exception_throw + 48
      2   Runner                              0x000000010ce707b1 -[FIRFirestore documentWithPath:] + 257
      3   Runner                              0x000000010d10662c getDocumentReference + 124
      4   Runner                              0x000000010d109879 -[FLTCloudFirestorePlugin handleMethodCall:result:] + 2665
      5   Flutter                             0x000000010e5b99a2 __45-[FlutterMethodChannel setMethodCallHandler:]_block_invoke + 115
      6   Flutter                             0x000000010e5d6616 _ZNK5shell21PlatformMessageRouter21HandlePlatformMessageEN3fml6RefPtrIN5blink15PlatformMessageEEE + 166
      7&lt;…&gt;
  </code></pre>
  
  <p>Lost connection to device.</p>