🐛 fixed error message code for HB translate helper (#15529)

closes: https://github.com/TryGhost/Ghost/issues/15500

- Per the issue, Ghost has a policy to never throw 500 Internal Server errors for theme issues. This change adds a check inside of `ghost\core\core\frontend\helpers\t.js` if `text` or `options` is undefined, to throw an `IncorrectUsageError` error within the function.
- Messaging was borrowed from `ghost\core\core\frontend\web\middleware\error-handler.js`.

ghost/core/core/frontend/helpers/t.js

@@ -11,8 +11,20 @@
 // {{tags prefix=(t " on ")}}
 
 const {themeI18n} = require('../services/handlebars');
+const errors = require('@tryghost/errors');
+const tpl = require('@tryghost/tpl');
+
+const messages = {
+    oopsErrorTemplateHasError: 'Oops, seems there is an error in the template.'
+};
 
 module.exports = function t(text, options) {
+    if (text === undefined && options === undefined) {
+        throw new errors.IncorrectUsageError({
+            message: tpl(messages.oopsErrorTemplateHasError)
+        });
+    }
+
     const bindings = {};
     let prop;
     for (prop in options.hash) {