Panic in go client when submission request fails / times out

[gregtws]

Observing a panic in the go client when it errors out during file submission.

When using the v1.0.0 go client function SubmitSampleFile to submit a file, the following error is returned to the caller:

triage: Post "https://private.tria.ge/api/v0/samples": dial tcp 51.15.123.173:443: i/o timeout

Then a panic occurs in sample.go:

Failed to submit file
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x666965]
goroutine 60344 [running]:
github.com/hatching/triage/go.(*Client).SubmitSampleFile.func1()
/go/pkg/mod/github.com/hatching/triage@v1.0.0/go/sample.go:108 +0xe5
created by github.com/hatching/triage/go.(*Client).SubmitSampleFile
/go/pkg/mod/github.com/hatching/triage@v1.0.0/go/sample.go:101 +0x3f2

The trace seems a bit confusing that it would fail on those lines (vs say in the defer or somewhere else). So probably needs a bit more digging to see whats going on and how to recover cleanly.

[gregtws]

Seeing another spate of these. Based on the trace, I suspect its due to unchecked errors in the multipart calls, but I don't have a good way to consistently reproduce:

// samples.go
		jsonField, _ := mw.CreateFormField("_json")
		jsonField.Write(request) // jsonField can be nil

		fileField, _ := mw.CreateFormFile("file", filename)
		io.Copy(fileField, file) // fileField can be nil