1. Improved error reporting for user login callback method.

app.py

@@ -416,6 +416,7 @@ def login():
 
 @app.route("/login_callback") # <path:subpath>/<code>
 def login_callback():
+    try:
         # print(f'code: {code}')
         token = None
         try:
@@ -464,6 +465,8 @@ def login_callback():
 
         print(f'user session: {session[Model_View_Base.KEY_USER]}')
         return redirect(f'{app.URL_HOST}{hash_callback}')
+    except Exception as e:
+        return jsonify({'status': 'failure', 'Message': f'Controller error.\n{e}'})
 
 @app.route("/logout")
 def logout():