Catch bad authentication in trusted_recording_signed_request

Return a failed authentication error in trusted_recording_signed_request
if the request doesn't include a signed request.

Author: cwarden

lib/cube/authentication.js

@@ -98,9 +98,9 @@ authentication.trusted_recording_signed_request = function(db, options) {
       return auth_ok({ anonymous: true});
     }
     var authHeader = request.headers.authorization;
-    var signedReq = signedRequest.parseSignedRequest(authHeader.substr(15));
-    var payload = signedReq.payload;
     try {
+      var signedReq = signedRequest.parseSignedRequest(authHeader.substr(15));
+      var payload = signedReq.payload;
       payload = signedRequest.deserializePayload(payload);
       auth_ok({
         email: payload.context.user.email,