improve token fetch

Dockerfile

@@ -8,7 +8,7 @@ WORKDIR /app
 COPY ./propedal-planner /app
 
 # Install any needed packages specified in requirements.txt
-RUN pip install --no-cache-dir -r requirements.txt
+RUN pip install -r requirements.txt
 
 # Make port available to the world outside this container
 EXPOSE 8001

propedal-planner/calendar_interface.py

@@ -13,6 +13,8 @@ except ImportError:
      from backports.zoneinfo import ZoneInfo
 
 WEEKDAYS= {0:"Mo", 1:"Di", 2:"Mi", 3:"Do", 4: "Fr", 5:"Sa", 6: "So"}
+result = None
+
 # Optional logging
 
 # logging.getLogger("msal").setLevel(logging.INFO)  # Optionally disable MSAL DEBUG logs
@@ -27,10 +29,9 @@ app = msal.ConfidentialClientApplication(
     )
 
 def get_access_token():
-    global app
+    global app, result
 
     # The pattern to acquire a token looks like this.
-    result = None
 
     # Firstly, looks up a token from cache
     # Since we are looking for token for the current app, NOT for an end user,