fix: handle translation API errors instead of panicking

[MrBeldum]

Problem

StrTranslate ignored the error from http.PostForm and then deferred resp.Body.Close(), so any network failure caused a nil pointer dereference. It also read translateResp.Data.Translations[0] before checking translateResp.Error.Code, so when the Google API returned an error response (invalid key, quota exceeded, etc.) the handler panicked with an index-out-of-range error and the Error.Message branch could never run.

go vet flags both the first issue (using resp before checking for errors) and a separate format bug in getGitterAvatarUrl, where username (a string) is printed with %d.

Fix

• Move the HTTP call into a small googleTranslate helper that returns an error for transport failures, body read failures, invalid JSON, API error responses, and empty translations arrays.
• StrTranslate now passes those errors back through TranslateData.ErrMsg, the field the frontend already reads, so it no longer panics.
• Use %s for username in the gitter avatar retry log.

Tests

Added object/translator_test.go, which runs googleTranslate against an httptest server for success, API error, empty result, non-JSON response, and unreachable endpoint cases. These tests don't need a database:

go test ./object/ -run TestGoogleTranslate -v

go vet ./object/ no longer reports either issue.

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[hsluoyz]

Thanks for spotting this! Both panics (nil resp on transport errors and the out-of-range Translations[0] on API errors) are real, and so is the %d format bug in the gitter log.

We've fixed it directly in 769a889 with a smaller change that keeps the logic inside StrTranslate. It also adds a request timeout, and the frontend now shows err_msg (it didn't read that field before, so errors would otherwise just show up as an empty translation). We'd rather not add test files to this repo, so closing this PR. Thanks again!