test: extra debug output for flaky failure case

[rvagg]

The flaky tests in CI are a 504, which should mean it's coming out of here:

lassie/pkg/server/http/ipfs.go

Line 235 in 2edae8b

errorResponse(res, statusLogger, http.StatusGatewayTimeout, fmt.Errorf("failed to fetch CID: %w", err))

The body should contain the error message.

[codecov-commenter]

Codecov Report

Merging #292 (4f676c7) into main (2edae8b) will increase coverage by 0.14%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #292      +/-   ##
==========================================
+ Coverage   72.52%   72.67%   +0.14%     
==========================================
  Files          68       68              
  Lines        6203     6203              
==========================================
+ Hits         4499     4508       +9     
+ Misses       1456     1450       -6     
+ Partials      248      245       -3     

see 7 files with indirect coverage changes

[rvagg]

Notable failure in CI for this: https://github.com/filecoin-project/lassie/actions/runs/5187581762/jobs/9351133526?pr=292

Not quite the same issue, it's failing during retrieval and we're getting the mime type 0 error so it must be a mid-retrieval error we're not seeing.

[hannahhoward]

Ouch I thought we'd resolved that one :(