Fix handling errors from other download instances

android/app/src/main/kotlin/com/nkming/nc_photos/DownloadEventChannelHandler.kt

@@ -59,7 +59,9 @@ class DownloadEventCompleteChannelHandler(context: Context) :
 				_eventSink?.error(
 					"downloadError",
 					"Download #$downloadId was not successful, status: $status, reason: $reason",
-					null
+					mapOf(
+						"downloadId" to downloadId
+					)
 				)
 			}
 		} else {
@@ -68,7 +70,9 @@ class DownloadEventCompleteChannelHandler(context: Context) :
 				"ID #$downloadId not found, user canceled the job?"
 			)
 			_eventSink?.error(
-				"userCanceled", "Download #$downloadId was canceled", null
+				"userCanceled", "Download #$downloadId was canceled", mapOf(
+					"downloadId" to downloadId
+				)
 			)
 		}
 	}

lib/mobile/android/download.dart

@@ -40,7 +40,16 @@ class DownloadEvent {
       .map((data) => DownloadCompleteEvent(
             data["downloadId"],
             data["uri"],
-          ));
+          ))
+      .handleError(
+    (e, stackTrace) {
+      throw AndroidDownloadError(e.details["downloadId"], e, stackTrace);
+    },
+    test: (e) =>
+        e is PlatformException &&
+        e.details is Map &&
+        e.details["downloadId"] is int,
+  );
 }
 
 class DownloadCompleteEvent {
@@ -49,3 +58,11 @@ class DownloadCompleteEvent {
   final int downloadId;
   final String uri;
 }
+
+class AndroidDownloadError implements Exception {
+  const AndroidDownloadError(this.downloadId, this.error, this.stackTrace);
+
+  final int downloadId;
+  final dynamic error;
+  final StackTrace stackTrace;
+}

lib/mobile/file_downloader.dart

@@ -62,7 +62,15 @@ class FileDownloader extends itf.FileDownloader {
         subscription = DownloadEvent.listenDownloadComplete()
           ..onData(onDownloadComplete)
           ..onError((e, stackTrace) {
+            if (e is AndroidDownloadError) {
+              if (e.downloadId != id) {
+                // not us, ignore
+                return;
+              }
+              completer.completeError(e.error, e.stackTrace);
+            } else {
               completer.completeError(e, stackTrace);
+            }
           });
         await completer.future;
       } finally {