Android: Printing.convertHtml hangs indefinitely on failure (Missing onLayoutFailed / onWriteFailed handling) #1897
Description
Describe the bug
On Android, when calling Printing.convertHtml, the Future sometimes never completes (hanging the UI with an infinite loader). This occurs when the Android PrintDocumentAdapter encounters an error during layout or writing.
Upon analyzing PdfConvert.java, I noticed that the LayoutResultCallback and WriteResultCallback only implement the onFinished methods. They miss the onFailed and onCancelled overrides.
Consequently, if the Android Print Manager fails (e.g., rendering error, memory issue), it calls onLayoutFailed, but since PdfConvert.java does not handle it, the result is never sent back to Flutter. The Dart MethodChannel waits indefinitely.