fix(das): validate the since query param instead of returning 500

[tryeverything24]

PR body — tryeverything24 — entrius/das-github-mirror

Branch: fix-miners-since-validation (in WSL Ubuntu-22.04 clone /root/dgm, commit 0e1c106, based on origin/test @ a188d3b)
Base: test
Title: fix(miners): validate since query param so malformed input returns 400, not 500

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Bug

GET /api/v1/miners/:githubId/pulls?since=... and GET /api/v1/miners/:githubId/issues?since=... pass the raw since query string straight into SQL, where it hits a timestamptz comparison (p.merged_at >= $2 etc.). Any value Postgres can't parse as a timestamp makes the query itself fail, so the endpoint returns 500 Internal Server Error for what is a malformed client input:

GET /api/v1/miners/1/pulls?since=banana   -> 500 (QueryFailedError: invalid input syntax for type timestamp with time zone)
GET /api/v1/miners/1/issues?since=        -> 500 (empty string binds "" into the $2::timestamptz IS NULL check)

MinersService.resolveSince only substitutes the default window when since is falsy — a present-but-garbage value is forwarded untouched. On the /issues GET path the controller forwards since ?? null, so even an empty since= binds "" and fails the cast.

This is inconsistent with the rest of the API: the POST variants of these same endpoints (parseSinceByRepo) and the dashboard controller both validate timestamps and return 400 with a clear message. It also matters for consumers: 5xx is conventionally retryable, so a client with a bad since will retry a request that can never succeed instead of surfacing its own bug.

Fix

Add parseSinceQuery() in the controller, applied to both GET endpoints:

• absent or empty since → undefined, preserving existing defaults (resolveSince window on /pulls, open-issue-load null mode on /issues);
• anything else must parse as a date, is normalized with toISOString() (same normalization as parseSinceByRepo and the dashboard controller), otherwise → BadRequestException ("since must be a valid ISO timestamp").

No service or SQL changes.

Tests

New miners.controller.spec.ts (unit, mocked MinersService):

• garbage since on /pulls and /issues → BadRequestException, service never called;
• valid since normalized to full ISO before reaching the service;
• omitted since → default window on /pulls, null on /issues;
• empty since= on /issues → treated as omitted (null) instead of binding "".

Written red-first against the current test tip: 5 of 7 cases fail before the fix, all pass after.

Local checks

• npm test — 32 passed (4 suites)
• npm run lint — clean
• npm run format:check — clean
• npm run build — clean