fix: don't let a failed browser launch override a successful runCheck result

Guard the finally block's re-await of browserPromise so a rejected
launch (e.g. Playwright can't start Chromium) doesn't rethrow out of
finally and override the try block's already-successful return value.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013gwc3aCiyQxmCWQke8RvEz

server.js

@@ -67,13 +67,15 @@ async function runCheck() {
     return results;
   } finally {
     if (browserPromise) {
-      const browser = await browserPromise;
+      const browser = await browserPromise.catch(() => null);
+      if (browser) {
         await browser.close().catch((err) => {
           console.error(`[check] kon de browser niet netjes sluiten: ${err && err.message}`);
         });
       }
     }
   }
+}
 
 startScheduler(runCheck);