Fix bug caused by empty avatar field

An empty avatar caused a request for the default icon to be fetched,
which caused the request for the user's letterhead to not be made.

components/app.vue

@@ -120,10 +120,9 @@ function getUser() {
 	}).then(b => {
 	    const validTypes = ['image/jpeg', 'image/png']
     
-        if (!validTypes.includes(b.type) || b.size <= 1) {
-            fetch("/assets/image/empty-avatar.jpg").
+        if (!b || !validTypes.includes(b.type) || b.size <= 1) {
+            return fetch("/assets/image/empty-avatar.jpg").
             then(r => r.blob()).then( a => this.user.avatar = a )
-            return
         }
         
         this.user.avatar = b
@@ -132,9 +131,8 @@ function getUser() {
 	    const validTypes = ['image/jpeg', 'image/png']
     
         if (!validTypes.includes(b.type) || b.size <= 1) {
-            fetch("/assets/image/empty-letterhead.jpg").
+            return fetch("/assets/image/empty-letterhead.jpg").
             then(r => r.blob()).then( a => this.user.letterhead = a )
-            return
         }
         
         this.user.letterhead = b