Fix iOS and Android behavior when an exception occures

@@ -43,7 +43,7 @@ public class PrintingHandler implements MethodChannel.MethodCallHandler {
             case "cancelJob": {
             case "cancelJob": {
                 final PrintingJob printJob =
                 final PrintingJob printJob =
                         new PrintingJob(activity, this, (int) call.argument("job"));
                         new PrintingJob(activity, this, (int) call.argument("job"));
-                printJob.cancelJob();
+                printJob.cancelJob(null);
                 result.success(1);
                 result.success(1);
                 break;
                 break;
             }
             }
@@ -125,18 +125,18 @@ public class PrintingHandler implements MethodChannel.MethodCallHandler {
                 if (result instanceof byte[]) {
                 if (result instanceof byte[]) {
                     printJob.setDocument((byte[]) result);
                     printJob.setDocument((byte[]) result);
                 } else {
                 } else {
-                    printJob.cancelJob();
+                    printJob.cancelJob("Unknown data received");
                 }
                 }
             }
             }
 
 
             @Override
             @Override
             public void error(String errorCode, String errorMessage, Object errorDetails) {
             public void error(String errorCode, String errorMessage, Object errorDetails) {
-                printJob.cancelJob();
+                printJob.cancelJob(errorMessage);
             }
             }
 
 
             @Override
             @Override
             public void notImplemented() {
             public void notImplemented() {
-                printJob.cancelJob();
+                printJob.cancelJob("notImplemented");
             }
             }
         });
         });
     }
     }

@@ -187,9 +187,10 @@ public class PrintingJob extends PrintDocumentAdapter {
         printJob = printManager.print(name, this, null);
         printJob = printManager.print(name, this, null);
     }
     }
 
 
-    void cancelJob() {
+    void cancelJob(String message) {
         if (callback != null) callback.onLayoutCancelled();
         if (callback != null) callback.onLayoutCancelled();
         if (printJob != null) printJob.cancel();
         if (printJob != null) printJob.cancel();
+        printing.onCompleted(PrintingJob.this, false, message);
     }
     }
 
 
     static void sharePdf(final Context context, final byte[] data, final String name) {
     static void sharePdf(final Context context, final byte[] data, final String name) {

@@ -45,8 +45,9 @@ public class PrintJob: UIPrintPageRenderer, UIPrintInteractionControllerDelegate
         }
         }
     }
     }
 
 
-    func cancelJob() {
+    func cancelJob(_ error: String?) {
         pdfDocument = nil
         pdfDocument = nil
+        printing.onCompleted(printJob: self, completed: false, error: error as NSString?)
     }
     }
 
 
     func setDocument(_ data: Data?) {
     func setDocument(_ data: Data?) {

@@ -139,10 +139,15 @@ public class PrintingPlugin: NSObject, FlutterPlugin {
 
 
         channel.invokeMethod("onLayout", arguments: arg, result: { (result: Any?) -> Void in
         channel.invokeMethod("onLayout", arguments: arg, result: { (result: Any?) -> Void in
             if result as? Bool == false {
             if result as? Bool == false {
-                printJob.cancelJob()
-            } else {
+                printJob.cancelJob(nil)
+            } else if result is FlutterError {
+                let error = result as! FlutterError
+                printJob.cancelJob(error.message)
+            } else if result is FlutterStandardTypedData {
                 let object = result as! FlutterStandardTypedData
                 let object = result as! FlutterStandardTypedData
                 printJob.setDocument(object.data)
                 printJob.setDocument(object.data)
+            } else {
+                printJob.cancelJob("Unknown data type")
             }
             }
         })
         })
     }
     }

@@ -44,26 +44,22 @@ class MethodChannelPrinting extends PrintingPlatform {
     switch (call.method) {
     switch (call.method) {
       case 'onLayout':
       case 'onLayout':
         final PrintJob job = _printJobs[call.arguments['job']];
         final PrintJob job = _printJobs[call.arguments['job']];
-        try {
-          final PdfPageFormat format = PdfPageFormat(
-            call.arguments['width'],
-            call.arguments['height'],
-            marginLeft: call.arguments['marginLeft'],
-            marginTop: call.arguments['marginTop'],
-            marginRight: call.arguments['marginRight'],
-            marginBottom: call.arguments['marginBottom'],
-          );
-
-          final Uint8List bytes = await job.onLayout(format);
+        final PdfPageFormat format = PdfPageFormat(
+          call.arguments['width'],
+          call.arguments['height'],
+          marginLeft: call.arguments['marginLeft'],
+          marginTop: call.arguments['marginTop'],
+          marginRight: call.arguments['marginRight'],
+          marginBottom: call.arguments['marginBottom'],
+        );
 
 
-          if (bytes == null) {
-            throw 'onLayout returned null';
-          }
+        final Uint8List bytes = await job.onLayout(format);
 
 
-          return Uint8List.fromList(bytes);
-        } catch (e) {
-          return e.toString();
+        if (bytes == null) {
+          throw 'onLayout returned null';
         }
         }
+
+        return Uint8List.fromList(bytes);
         break;
         break;
       case 'onCompleted':
       case 'onCompleted':
         final bool completed = call.arguments['completed'];
         final bool completed = call.arguments['completed'];

@@ -101,7 +101,9 @@ public class PrintJob: NSView, NSSharingServicePickerDelegate {
         )
         )
     }
     }
 
 
-    public func cancelJob() {}
+    func cancelJob(_ error: String?) {
+        printing.onCompleted(printJob: self, completed: false, error: error as NSString?)
+    }
 
 
     public static func sharePdf(data: Data, withSourceRect rect: CGRect, andName name: String) {
     public static func sharePdf(data: Data, withSourceRect rect: CGRect, andName name: String) {
         let tempFile = NSTemporaryDirectory() + name
         let tempFile = NSTemporaryDirectory() + name

@@ -139,10 +139,15 @@ public class PrintingPlugin: NSObject, FlutterPlugin {
 
 
         channel.invokeMethod("onLayout", arguments: arg, result: { (result: Any?) -> Void in
         channel.invokeMethod("onLayout", arguments: arg, result: { (result: Any?) -> Void in
             if result as? Bool == false {
             if result as? Bool == false {
-                printJob.cancelJob()
-            } else {
+                printJob.cancelJob(nil)
+            } else if result is FlutterError {
+                let error = result as! FlutterError
+                printJob.cancelJob(error.message)
+            } else if result is FlutterStandardTypedData {
                 let object = result as! FlutterStandardTypedData
                 let object = result as! FlutterStandardTypedData
                 printJob.setDocument(object.data)
                 printJob.setDocument(object.data)
+            } else {
+                printJob.cancelJob("Unknown data type")
             }
             }
         })
         })
     }
     }