Added output to the get helper when the timeout is exceeded

refs https://linear.app/tryghost/issue/ENG-670

ghost/core/core/frontend/helpers/get.js

@@ -2,7 +2,7 @@
 // Usage: `{{#get "posts" limit="5"}}`, `{{#get "tags" limit="all"}}`
 // Fetches data from the API
 const {config, api, prepareContextResource} = require('../services/proxy');
-const {hbs} = require('../services/handlebars');
+const {hbs, SafeString} = require('../services/handlebars');
 
 const logging = require('@tryghost/logging');
 const errors = require('@tryghost/errors');
@@ -154,7 +154,7 @@ async function makeAPICall(resource, controllerName, action, apiOptions) {
                         }
                     }));
 
-                    resolve({[resource]: []});
+                    resolve({[resource]: [], '@@ABORTED_GET_HELPER@@': true});
                 }, threshold);
             });
 
@@ -242,10 +242,16 @@ module.exports = async function get(resource, options) {
             }
     
             // Call the main template function
-            return options.fn(response, {
+            const rendered = options.fn(response, {
                 data: data,
                 blockParams: blockParams
             });
+
+            if (response['@@ABORTED_GET_HELPER@@']) {
+                return new SafeString(`<span data-aborted-get-helper>Could not load content</span>` + rendered);
+            } else {
+                return rendered;
+            }
         });
         return result;
     } catch (error) {

ghost/core/test/unit/frontend/helpers/get.test.js

@@ -1,3 +1,4 @@
+const assert = require('assert');
 const should = require('should');
 const sinon = require('sinon');
 const {SafeString} = require('../../../../core/frontend/services/handlebars');
@@ -21,7 +22,9 @@ describe('{{#get}} helper', function () {
     });
 
     beforeEach(function () {
-        fn = sinon.spy();
+        fn = sinon.spy(function () {
+            return '';
+        });
         inverse = sinon.spy();
 
         locals = {root: {}, globalProp: {foo: 'bar'}};
@@ -394,12 +397,13 @@ describe('{{#get}} helper', function () {
         it('should log an error and return safely if it hits the timeout threshold', async function () {
             configUtils.set('optimization:getHelper:timeout:threshold', 1);
 
-            await get.call(
+            const result = await get.call(
                 {},
                 'posts',
                 {hash: {}, data: locals, fn: fn, inverse: inverse}
             );
 
+            assert(result.toString().includes('data-aborted-get-helper'));
             // A log message will be output
             logging.error.calledOnce.should.be.true();
             // The get helper gets called with an empty array of results