Stop interpreting after handling login

Fixes #105.

package.json

@@ -1,6 +1,6 @@
 {
     "name": "fwdekker.com",
-    "version": "0.25.6",
+    "version": "0.25.7",
     "description": "The source code of [my personal website](https://fwdekker.com/).",
     "author": "Felix W. Dekker",
     "repository": {

src/main/js/Shell.ts

@@ -144,6 +144,7 @@ export class Shell {
                 this.attemptUser = undefined;
             }
             this.saveState();
+            return;
         }
 
         this.inputHistory.add(inputString);