An argument out of range exception is thrown when invalid JSON is passed to a FE endpoint.

[hoxhaerin]

This line here:

FastEndpoints/Src/Library/Endpoint/Endpoint.cs

Line 106 in baab0c4

ValidationFailures.Add(new(x.Path?[2..] ?? "Unknown", x.InnerException?.Message ?? "Unknown de-serialization error!"));

more specifically this part: [2..], throws an ArgumentOutOfRangeException | startIndex cannot be larger than length of string. (Parameter 'startIndex') when you add an extra comma at the end of the JSON request.

{
  "code": "A001",
  "name": "",
  "marketingName": "fsa",
}

I'd open a PR myself but I don't know why you have added that index there and how you'll want to handle it, so I'm just leaving this here.

[dj-nitehawk]

fixed in v5.7.2.8-beta
thanks for reporting!