sentry: Stacks are returned most-recent last.

Per [1], the sentry API returns frames sorted from oldest to newest.
As such, matching against the first filename that matches is most
likely not the right frame.

Match against the last frame with the guilty filename.

[1] https://develop.sentry.dev/sdk/event-payloads/stacktrace/

zerver/webhooks/sentry/tests.py

@@ -44,17 +44,14 @@ Traceback:
 
 Traceback:
 ```javascript
-     const Sentry = require('@sentry/node');
-
-     Sentry.init({
        dsn: 'https://redacted.ingest.sentry.io/5216640',
      });
 
----> Sentry.withScope(function(scope) {
+     Sentry.withScope(function(scope) {
        scope.addEventProcessor(function(event, hint) {
          return event;
        });
-       Sentry.captureException(new Error('Sample error from node.'));
+--->   Sentry.captureException(new Error('Sample error from node.'));
      });
 
 

zerver/webhooks/sentry/view.py

@@ -119,7 +119,7 @@ def handle_event_payload(event: Dict[str, Any]) -> Tuple[str, str]:
 
         if stacktrace:
             exception_frame = None
-            for frame in stacktrace["frames"]:
+            for frame in reversed(stacktrace["frames"]):
                 if frame["filename"] == filename:
                     exception_frame = frame
                     break