bug(auth): Fix issue where errors are being reported that should be repressed.

Because:
- After adding tracing and upgrading sentry it appears errors can propagate in other ways.

This Commit:
- Moves the ignoreError check into the error module
- Runs the ignoreError check in the filterEvents function that runs on before send.

packages/fxa-auth-server/lib/error.js

@@ -1594,5 +1594,47 @@ function appErrorFromOauthError(err) {
   }
 }
 
+// Maintain list of errors that should not be sent to Sentry
+const IGNORED_ERROR_NUMBERS = [
+  ERRNO.BOUNCE_HARD,
+  ERRNO.BOUNCE_SOFT,
+  ERRNO.BOUNCE_COMPLAINT,
+];
+
+/**
+ * Prevents errors from being captured in sentry.
+ *
+ * @param {Error} error An error with an error number. Note that errors of type vError will
+ *                use the underlying jse_cause error if possible.
+ */
+function ignoreErrors(error) {
+  if (!error) {
+    return;
+  }
+
+  // Prefer jse_cause, but fallback to top level error if needed
+  const statusCode =
+    determineStatusCode(error.jse_cause) || determineStatusCode(error);
+
+  const errno = error.jse_cause?.errno || error.errno;
+
+  // Ignore non 500 status codes and specific error numbers
+  return statusCode < 500 || IGNORED_ERROR_NUMBERS.includes(errno);
+}
+
+/**
+ * Given an error tries to determine the HTTP status code associated with the error.
+ * @param {*} error
+ * @returns
+ */
+function determineStatusCode(error) {
+  if (!error) {
+    return;
+  }
+
+  return error.statusCode || error.output?.statusCode || error.code;
+}
+
 module.exports = AppError;
 module.exports.ERRNO = ERRNO;
+module.exports.ignoreErrors = ignoreErrors;

packages/fxa-auth-server/lib/monitoring.js

@@ -10,6 +10,7 @@ const logger = require('./log')(
   'configure-sentry'
 );
 const { version } = require('../package.json');
+const { ignoreErrors } = require('./error');
 
 /**
  * Initialize sentry & otel
@@ -40,6 +41,14 @@ const URIENCODEDFILTERED = encodeURIComponent(FILTERED);
  * @param {Sentry.Event} event
  */
 function filterSentryEvent(event, hint) {
+  // If we encounter a WError, we likely want to filter it out. These errors are
+  // intentionally relayed to the client, and don't constitute unexpected errors.
+  // Note, that these might arrive here from our reportSentryError function, or
+  // some other instrumentation that has captured the error.
+  if (hint?.originalException != null && ignoreErrors(hint.originalException)) {
+    return null;
+  }
+
   if (event.breadcrumbs) {
     for (const bc of event.breadcrumbs) {
       if (bc.message) {

packages/fxa-auth-server/lib/sentry.js

@@ -7,7 +7,8 @@
 const Hoek = require('@hapi/hoek');
 const Sentry = require('@sentry/node');
 const verror = require('verror');
-const { ERRNO } = require('./error');
+const { ignoreErrors } = require('./error');
+
 const {
   formatMetadataValidationErrorMessage,
   reportValidationError,
@@ -17,13 +18,6 @@ const {
 const TOKENREGEX = /[a-fA-F0-9]{32,}/gi;
 const FILTERED = '[Filtered]';
 
-// Maintain list of errors that should not be sent to Sentry
-const IGNORED_ERROR_NUMBERS = [
-  ERRNO.BOUNCE_HARD,
-  ERRNO.BOUNCE_SOFT,
-  ERRNO.BOUNCE_COMPLAINT,
-];
-
 function reportSentryError(err, request) {
   let exception = '';
   if (err && err.stack) {
@@ -149,40 +143,6 @@ async function configureSentry(server, config, processName = 'key_server') {
   }
 }
 
-/**
- * Prevents errors from being captured in sentry.
- *
- * @param {Error} error An error with an error number. Note that errors of type vError will
- *                use the underlying jse_cause error if possible.
- */
-function ignoreErrors(error) {
-  if (!error) {
-    return;
-  }
-
-  // Prefer jse_cause, but fallback to top level error if needed
-  const statusCode =
-    determineStatusCode(error.jse_cause) || determineStatusCode(error);
-
-  const errno = error.jse_cause?.errno || error.errno;
-
-  // Ignore non 500 status codes and specific error numbers
-  return statusCode < 500 || IGNORED_ERROR_NUMBERS.includes(errno);
-}
-
-/**
- * Given an error tries to determine the HTTP status code associated with the error.
- * @param {*} error
- * @returns
- */
-function determineStatusCode(error) {
-  if (!error) {
-    return;
-  }
-
-  return error.statusCode || error.output?.statusCode || error.code;
-}
-
 module.exports = {
   configureSentry,
   reportSentryError,