UTF-8 error when sending non UTF-8 encoded body

[UlrichRaab]

Describe the bug
I must use a AWS S3 presigned upload URL to upload an image to S3 (PUT request). The request body is the raw bytes of that image. The bytes are not UTF-8 encoded. The request fails with FormatException: Invalid UTF-8 byte (at offset 0)

My code for the request:

final bytes = await File(file.path).readAsBytes();
final url = Uri.parse(uploadUrl);
final request = Request('PUT', url)
  ..headers['Content-Type'] = file.mimeType
  ..headers['x-amz-checksum-sha256'] = file.sha256
  ..bodyBytes = bytes;
final stream = await httpClient.send(request);
final response = await Response.fromStream(stream);
return UploadFileResponse.fromHttpResponse(response);

The stacktrace:

Upload image failed
I/flutter (28409): ↳ FormatException: Invalid UTF-8 byte (at offset 0)
I/flutter (28409): ↳ #0      _Utf8Decoder.convertSingle (dart:convert-patch/convert_patch.dart:1860:7)
I/flutter (28409):   #1      Utf8Decoder.convert (dart:convert/utf.dart:350:37)
I/flutter (28409):   #2      Utf8Codec.decode (dart:convert/utf.dart:63:20)
I/flutter (28409):   #3      Request.body (package:http/src/request.dart:102:31)
I/flutter (28409):   #4      RequestCopyWith.copyWith (package:http_interceptor/extensions/request.dart:24:20)
I/flutter (28409):   #5      BaseRequestCopyWith.copyWith (package:http_interceptor/extensions/base_request.dart:38:47)
I/flutter (28409):   #6      InterceptedClient._interceptRequest (package:http_interceptor/http/intercepted_client.dart:311:46)

I think the error happens because you copy the body in your copyWith extension of Request. Using bodyBytes instead should fix the problem.

To Reproduce
Steps to reproduce the behavior:

1. Try to send raw bytes to an endpoint using a PUT request

Expected behavior
No UTF-8 Format exception

Screenshots
No screenshot

Please complete the following information):

• Flutter version: [3.38.8]
• IDE [VS Code]
• http_interceptor Version [2.0.0]

Additional context
Add any other context about the problem here.