Fixed default user images returning 404s

no issue
- dropping IE11 support meant that babel/uglifyjs was able to be clever and inline the image URLs variables directly into the template strings which was then breaking the fingerprint asset rewriting resulting in files having hashes but file references in the JS not having the hash
- removing use of template strings to build the default image URLs prevents the inlining behaviour, letting the asset fingerprint plugin do it's thing correctly

app/components/gh-profile-image.js

@@ -46,7 +46,7 @@ export default Component.extend({
         this._super(...arguments);
 
         let defaultImage = '/img/user-image.png';
-        this._defaultImageUrl = `${this.get('ghostPaths.assetRoot')}${defaultImage}`;
+        this._defaultImageUrl = this.get('ghostPaths.assetRoot').replace(/\/$/, '') + defaultImage;
         this._setPlaceholderImage(this._defaultImageUrl);
     },
 

app/models/user.js

@@ -83,14 +83,14 @@ export default Model.extend(ValidationEngine, {
     profileImageUrl: computed('ghostPaths.assetRoot', 'profileImage', function () {
         // keep path separate so asset rewriting correctly picks it up
         let defaultImage = '/img/user-image.png';
-        let defaultPath = `${this.ghostPaths.assetRoot.replace(/\/$/, '')}${defaultImage}`;
+        let defaultPath = this.ghostPaths.assetRoot.replace(/\/$/, '') + defaultImage;
         return this.profileImage || defaultPath;
     }),
 
     coverImageUrl: computed('ghostPaths.assetRoot', 'coverImage', function () {
         // keep path separate so asset rewriting correctly picks it up
         let defaultImage = '/img/user-cover.png';
-        let defaultPath = `${this.ghostPaths.assetRoot.replace(/\/$/, '')}${defaultImage}`;
+        let defaultPath = this.ghostPaths.assetRoot.replace(/\/$/, '') + defaultImage;
         return this.coverImage || defaultPath;
     }),