fix(sigretests.filterOptionalJobs): consider http status

[dhiller]

What this PR does / why we need it:

Adds a missing http status check when filtering for optional lanes.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #106

Special notes for your reviewer:

/cc @dollierp

[sourcery-ai]

Hey - I've found 1 issue, and left some high level feedback:

• In filterOptionalJobs, you access prowJobJSON.StatusCode before checking the err from http.Get; swap the order so you return on error before dereferencing a potentially nil response.
• When skipping non-200 responses in filterOptionalJobs, make sure to close prowJobJSON.Body before continue, and consider replacing the per-iteration defer prowJobJSON.Body.Close() with an explicit Close() to avoid accumulating open connections in the loop.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- In `filterOptionalJobs`, you access `prowJobJSON.StatusCode` before checking the `err` from `http.Get`; swap the order so you return on error before dereferencing a potentially nil response.
- When skipping non-200 responses in `filterOptionalJobs`, make sure to close `prowJobJSON.Body` before `continue`, and consider replacing the per-iteration `defer prowJobJSON.Body.Close()` with an explicit `Close()` to avoid accumulating open connections in the loop.

## Individual Comments

### Comment 1
<location> `pkg/sigretests/main.go:169-170` </location>
<code_context>
 	var filteredJobs []job
 	for _, j := range unfilteredJobs {
 		prowJobJSON, err := http.Get(fmt.Sprintf(prowJobJSONURL, org, repo, prNumber, j.jobName, j.buildNumber))
+		if prowJobJSON.StatusCode != 200 {
+			continue
+		}
</code_context>

<issue_to_address>
**issue (bug_risk):** StatusCode is accessed before checking `err`, which can panic if `http.Get` fails.

If `http.Get` returns an error, `prowJobJSON` will be nil and accessing `prowJobJSON.StatusCode` will panic. You should check `err` before using the response, then check `StatusCode`, e.g.:

```go
prowJobJSON, err := http.Get(fmt.Sprintf(prowJobJSONURL, org, repo, prNumber, j.jobName, j.buildNumber))
if err != nil {
	return nil, err
}
if prowJobJSON.StatusCode != http.StatusOK {
	prowJobJSON.Body.Close()
	continue
}
defer prowJobJSON.Body.Close()
```
</issue_to_address>

---

Sourcery is free for open source - if you like our reviews please consider sharing them ✨

• X
• Mastodon
• LinkedIn
• Facebook

_{Help me be more useful! Please click 👍 or 👎 on each comment and I'll use the feedback to improve your reviews.}

[sourcery-ai]

issue (bug_risk): StatusCode is accessed before checking err, which can panic if http.Get fails.

If http.Get returns an error, prowJobJSON will be nil and accessing prowJobJSON.StatusCode will panic. You should check err before using the response, then check StatusCode, e.g.:

prowJobJSON, err := http.Get(fmt.Sprintf(prowJobJSONURL, org, repo, prNumber, j.jobName, j.buildNumber))
if err != nil {
	return nil, err
}
if prowJobJSON.StatusCode != http.StatusOK {
	prowJobJSON.Body.Close()
	continue
}
defer prowJobJSON.Body.Close()

[dollierp]

s/200/http.StatusOK/