fix: downgrade transient PubSub poll errors from error to warn

ETIMEDOUT and similar network errors are expected for long-polling
connections to Google Pub/Sub. Downgrade these to warn level so they
no longer appear in Bugsnag, and return instead of throwing so the
poll loop restarts immediately without the 3s error delay.

Author: andris9

lib/oauth/pubsub/google.js

@@ -202,6 +202,11 @@ class PubSubInstance {
 
             await oauth2Apps.setMeta(this.app, { pubSubFlag: null });
         } catch (err) {
+            // Transient network errors are expected for long-polling connections
+            if (['ETIMEDOUT', 'ECONNRESET', 'ECONNREFUSED', 'UND_ERR_SOCKET', 'UND_ERR_CONNECT_TIMEOUT'].includes(err.code)) {
+                logger.warn({ msg: 'Transient error pulling subscription messages', app: this.app, code: err.code });
+                return;
+            }
             logger.error({ msg: 'Failed to pull subscription messages', app: this.app, err });
             throw err;
         }