Import a backup isn't working

[MaxSchlueter]

Describe the bug
Importing a backup that I've previously exported to a file isn't working, the workout doesn't show up in the list.

To Reproduce
Steps to reproduce the behavior:

1. Go to Settings
2. Click on "Import a backup"
3. Selected a previously exported workout
4. The previously exported workout doesn't show up in the list of workouts

Expected behavior
Would expect the workout to show up in the list.

Smartphone (please complete the following information):

• Device: Google Pixel 2
• OS: Android 11

[blockbasti]

Did you create the backup by exporting a workout or did you just copy the files from the data folder?

[MaxSchlueter]

I created the backup by exporting a workout.

[blockbasti]

I can't reproduce this on my device. Can you provide me with the backup file, so i can try it myself?

[MaxSchlueter]

Sure, this is the content of the exported workout (Test.json):

{
  "workouts": [
    {
      "title": "Test",
      "sets": [
        {
          "repetitions": 1,
          "id": "265d3e45-1f21-49ea-b9d4-7336f968cb3a",
          "exercises": [
            {
              "name": "Exercise",
              "id": "73492695-08a3-487f-b52a-cb9cc5051a63",
              "duration": 30
            }
          ]
        }
      ],
      "version": 2,
      "position": 10
    }
  ]
}

[blockbasti]

I imported the file successfully on my real device and dev emulator.

[MaxSchlueter]

I could import the file successfully as well on my old smartphone which is running Android 7. It's still not working on my current one, a Pixel 2 running Android 11 (Lineage OS).

[Franziskus1988]

I'm using a Xiaomi Mi 8 with the latest Lineage OS 18.1 and it is not working, too.

[Franziskus1988]

@blockbasti

So, I debugged the app and the importing and I think I found the problem:
In storage_helper.dart:48 you are importing the data with the

var backup = await File(filePath).readAsString();

In my case this throws an exception due to an malformed utf8 encoding. I'm not very experienced in Android/Flutter development so I "DuckDuckGo-ed" and found a similar problem here: dart-lang/pana#759

After changing the above code to

    var bytes = await File(filePath).readAsBytes();
    var backup = utf8.decode(bytes, allowMalformed: true);

it works perfectly fine! Of course you could follow the discussion from the mentioned link to write this a little bit nicer and don't allowMalformed per default ;)

Hope this helped.

[blockbasti]

@Franziskus1988 thank you for finding this. Could you please create a pull request with these changes?