I was following a crash course on flutter and got this weird error.
terminal error display in visual studio code.
Android error display
main.dart
answer.dart
question.dart
quiz.dart
resullt.dart
Please remove me
Future<void> _onDelete(String token) async {
print('this is sample code');
}
You are passing null to a Text() widget. To avoid this error, you can either null check or you can do this to show an empty string on null: Text(yourString ?? '');
Related
I'm working on the chrome.debugger Chrome extensions API, here's the simple example:
chrome.debugger.attach(target, "1.2")
chrome.debugger.sendCommand(target, "Input.insertText", { text: "test." })
chrome.debugger.detach(target, "1.2")
And in the last line, I get the error:
VM7521:1 Uncaught TypeError: Error in invocation of debugger.detach(debugger.Debuggee target, optional function callback): No matching signature.
at <anonymous>:1:17
What's the problem here?
I guess I've solved the problem:
chrome.debugger.detach(target)
Instead of
chrome.debugger.detach(target, "1.2")
I noticed this while reading the Chrome extension samples on Github:
chrome-extensions-samples/background.js at e716678b67fd30a5876a552b9665e9f847d6d84b ยท GoogleChrome/chrome-extensions-samples
It didn't have the "version" argument in the detach so.
Hope this helps.
Close visual studio and open, it should solve your problem
I keep running into an error in the console when my $mdToast fires. It says: TypeError: [$q:qcycle] Expected promise to be resolved with value other than itself '{}' The toast works fine, but I would prefer not to have that error whenever it pops up. Here is the function:
let showSuccess = this.mdToast.show({
template: '<md-toast>User added successfully!</md-toast>',
hideDelay: 33000,
position: 'top'
});
this.mdToast.hide(showSuccess);
Does anyone know what might be causing this? Thanks
You don't need to pass toast itself to hide function. Just use it without any parameters:
this.mdToast.hide();
According to the reference it hides an existing toast. Optional response parameter is actually used for another purpose (promises).
$mdToast.hide([response]);
Hide an existing toast and resolve the promise returned from $mdToast.show().
My UWP app is crashing in Release mode and works fine in Debug mode but I can't put my finger on what the issue is but I know it's related to a combination of raising an event from System.Threading.Timer and MVVMLight.
I created an new dummy application and use the same code (ZXing.net.mobile where I used 2 portable libraries and I used my own user control which is a simplified version of theirs - I'm using events instead of <Action>). This works fine and I'm currently trying to put more steps into it i.e. include mvvmlight and navigation but so far, I can't reproduce the problem in this dummy app.
The error I'm getting is:
Unhandled exception at 0x58C1AF0B (mrt100_app.dll) in Company.MyApp.App.exe:
0xC0000602: A fail fast exception occurred. Exception handlers will not be
invoked and the process will be terminated immediately.
Followed by:
Unhandled exception at 0x0107D201 (SharedLibrary.dll) in
Company.MyApp.App.exe: 0x00001007.
When looking at the Threads window, one of the worker thread has the following information if that's of help.
Not Flagged > 4012 0 Worker Thread <No Name>
System.Private.Interop.dll!System.Runtime.InteropServices.
ExceptionHelpers.ReportUnhandledError Normal
[External Code]
System.Private.Interop.dll!System.Runtime.InteropServices.ExceptionHelpers.
ReportUnhandledError(System.Exception e) Line 885
System.Private.Interop.dll!Internal.Interop.InteropCallbacks.ReportUnhandledError
(System.Exception ex) Line 17
System.Private.WinRTInterop.CoreLib.dll!Internal.WinRT.Interop.WinRTCallbacks.
ReportUnhandledError(System.Exception ex) Line 274
System.Private.CoreLib.dll!System.RuntimeExceptionHelpers.ReportUnhandledException
(System.Exception exception) Line 152
System.Private.Threading.dll!System.Threading.Tasks.AwaitTaskContinuation.
ThrowAsyncIfNecessary(System.Exception exc) Line 784
System.Private.Threading.dll!System.Threading.WinRTSynchronizationContext.Invoker.
InvokeCore() Line 182
System.Private.Threading.dll!System.Threading.WinRTSynchronizationContext.Invoker.
Invoke(object thisObj) Line 162
System.Private.CoreLib.dll!System.Action<System.__Canon>.
InvokeOpenStaticThunk(System.__Canon obj)
System.Private.WinRTInterop.CoreLib.dll!Internal.WinRT.Interop.WinRTCallbacks.PostToCoreDispatcher.AnonymousMethod__0() Line 266
MyCompany.MyApp.App.exe
MyCompany.MyApp.App.ViewModels.ValidateHandler.Invoke(string pin)
MyCompany.MyApp.App.McgInterop.dll!McgInterop.ReverseComSharedStubs
.Proc_(object __this, System.IntPtr __methodPtr) Line 6163
MyCompany.MyApp.App.McgInterop.dll!Windows.UI.Core.DispatchedHandler__Impl.Vtbl.Invoke__STUB(System.IntPtr pComThis) Line 45147
[External Code]
Within my QR Code UserControl, it's using a System.Threading.Timer and it raises an event when a QR Code is found:
timerPreview = new Timer(async (state) =>
{
....
// Check if a result was found
if (result != null && !string.IsNullOrEmpty(result.Text))
{
Debug.WriteLine("Barcode Found: " + result.Text);
if (!this.ContinuousScanning)
{
delay = Timeout.Infinite;
await StopScanningAsync();
}
else
{
delay = this.ScanningOptions.DelayBetweenContinuousScans;
}
OnBarcodeFound(result.Text);
}
timerPreview.Change(delay, Timeout.Infinite);
}, null,
this.ScanningOptions.InitialDelayBeforeAnalyzingFrames,
Timeout.Infinite);
In the page that host the QRCode UserControl, I've got the following code:
private async void ScannerControl_BarcodeFound(string barcodeValue)
{
var dispatcher = CoreApplication.MainView.CoreWindow.Dispatcher;
await dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () => {
Debug.WriteLine(barcodeValue);
GetViewModel.BarcodeFound(barcodeValue);
});
}
As you can see, I'm passing the QrCode value to my ViewModel and from there, I sent a message and then re-direct to another page:
public void BarcodeFound(string barcodeData)
{
Messenger.Default.Send<string>(barcodeData, MessengerTokens.QrCodeFound);
this.NavigationFacade.NavigateToMyOtherPage();
}
I could keep going and provide additional code, but as I add additional breakpoints I can see that the code and passing the correct value and going to the correct location but eventually it throws this error. If I add additional error handlers or dispatcher code, it eventually works and goes to the next page as expected but when I click on a button in my CommandBar, it then takes a while and it eventually throws the same error, so by adding these additional bits of code, I feel I'm just pushing down the problem further down the line.
Anyone got any suggestions on how I get around this problem. I wish I could share the full app but definitely can't. So I know it will be hard to provide a solution, but if anyone has suggestions I'd appreciate them.
As I said, I think the issue is a result of a combination of threading and mvvmlight but it's driving me nuts that my test app so far is working exactly as expected, so I'm pretty sure it's not Zxing or my UserControl.
Any help, suggestions would be greatly appreciated or if you need me to provide additional info, please let me know what and I'll try to provide it.
Thanks.
Well, this was a painstaking exercise and a huge waste of my time!
It was down to a few things!!
I was using a different DataService in Releasemode which wasn't implemented. By implemented, I mean all my functions were returning the NotImplementedException or null values.
When passing my model to my ViewModel, I did not check if it was null, thus causing unhandled exceptions.
I had a chain of mvvmlight events (Messenger.Default.Send<>) being triggered and none were checking for error or null values.
While all of these were caused by poor validation from my part, these errors are extremely poorly reported in Release mode! if from the get go, I had received a NullReferenceException or any kind of exceptions, it would have put me in the right direction immediately, but throwing errors such as the one I've had were totally useless but it didn't but lesson learned!!
All I can say is that if this problem ever happens to you, don't waste your time rewriting code or trying to find workarounds. First work your way through your workflow/chain of events and hopefully, you'll eventually catch the culprit.
Hope this helps.
Sadly we were facing a similar issue, ours was involved with setting the qualifier values for changing localization on the fly in the app but came up with mystery fail fast/SharedLibrary native errors. Upgrading the Microsoft.NETCore.UniversalWindowPlatform package from 6.0.4 to 6.0.7 seems to have resolved the issue.
Only thought of this because another place I was researching this error involved someone solving a SharedLibrary problem by upgrading their NETCore package, that case was an earlier one (5.x), but figured it was worth a shot.
In the below example, infoScroller is a UIWebView and println(HTMLDescription) prints a lovely string of HTML. However, the attempt to loadHTMLString gets the runtime error: fatal error: Can't unwrap Optional.None
if let HTMLDescription = self.myData?.content? {
println(HTMLDescription)
infoScroller.loadHTMLString(HTMLDescription, baseURL: nil)
}
I've tried every combination of ! and ? in both the assignment and use of the string but I get this same error every time, though the variable never fails to print out perfectly to the console.
There is another value that I set using the same method and it works fine. Both are strings, but the other one is more simple in that HTMLDescription is multiline and the working one is not.
Edit: The discussion in the comments prompted me to check the infoScroller and it's description as printed in the console is: (#sil_weak UIWebView!) infoScroller =
I'm thinking that's the issue, but I'm not sure what it means or how to fix it.
Edit 2: This has to be the issue. println(infoScroller.description) yields the exact same error.
Got it! This question put me on the path. I was trying to load the content before the view was fully loaded. Moved loadHTMLString() into viewDidLoad(). Stupid simple.
I've made a plugin for my android project, but I get the error Error: Status=2 Message=Class not found. I'm using another plugin from phonegap-plugins/android repository successfully. When I made my own I copied the files from the plugin that already works to get the function/method names etc. right. I have googled and looked "everywhere", but can't figure it out.
The javafile is called EmailSender.java, extends Plugin and is placed in src/phonegap/plugins/emailSender.
In my plugins.xml I have this line:
<plugin name="EmailSender" value="phonegap.plugins.emailSender.EmailSender"/>
emailsender.js
var EmailSender = function() {
}
EmailSender.prototype.sendMail = function(day, time, email) {
return PhoneGap.exec(null, null, 'emailSender', 'sendMail', [day, time, email]);
};
PhoneGap.addConstructor(function() {
PhoneGap.addPlugin("emailSender", new EmailSender());
});
just check out this link as it is sample for the intent plugin so by passing intent default chooser options will be pop up. please clarify more if you want other things.
https://github.com/purplecabbage/phonegap-plugins/tree/master/Android/WebIntent