[BUG] Tile fallback feature throws error on failure when fallbackUrl not defined

[envomer]

What is the bug?

First thanks for the great library!

I upgraded to flutter_map 5.0.0 and now i am getting errors thrown if a tile image does not exist.
This error to be precise: flutter: Invalid argument(s): No host specified in URI

After taking a deeper look, this error is being generated from FlutterMapNetworkImageProvider provider.

When a tile does not exist on the remote server, the httpClient will throw an exception which will be caught and the _loadAsync will be called again with the useFallback argument. IT will try to use the fallback url, but when no fallback url is defined it will use an empty string. That however will throw a No host specified in URI error. Does it even make sense to retry if no fallback url is defined?

// tile_provider.dart:59
  Future<Codec> _loadAsync(
    FlutterMapNetworkImageProvider key,
    StreamController<ImageChunkEvent> chunkEvents,
    ImageDecoderCallback decode, {
    bool useFallback = false,
  }) async {
    final Uint8List bytes;
    try {
      bytes = await httpClient.readBytes(
        Uri.parse(useFallback ? fallbackUrl ?? '' : url),
        headers: headers,
      );
    } catch (_) {
      if (useFallback) rethrow;
      return _loadAsync(key, chunkEvents, decode, useFallback: true);
    }

    return decode(await ImmutableBuffer.fromUint8List(bytes));
  }
  

How can we reproduce it?

• Load a map with missing tiles

Use the following tile provider:

TileLayer(
      urlTemplate: info.url,
      backgroundColor: Colors.black,
      additionalOptions: const {'noWrap': 'true'},
      reset: resetController.stream,
      panBuffer: 1,
    );

Do you have a potential solution?

Maybe a retry should only be triggered if a fallback is set? What do you think?

Platforms

MacOS

Severity

Minimum: Allows normal functioning

[JaffaKetchup]

Hi @envomer,
I do believe this to be a bug. Thanks for reporting!