fix no config file handling

main.py

@@ -51,14 +51,19 @@ async def main() -> None:
     try:
         with open('texlily.yaml', 'r') as conf:
             config = yaml.safe_load(conf)
+            # if config file does not exist, quit
     except FileNotFoundError:
             print("No config file found.\nPlease create a file named `texlily.yaml` and read the README file.")
             quit()
-    # Retrieve our configuration.
-    homeserver = str(config["homeserver"])
-    user = str(config["user"])
-    token = str(config["token"])
-    path = str(config["path"])
+    try:
+        # Retrieve our configuration
+        homeserver = str(config["homeserver"])
+        user = str(config["user"])
+        token = str(config["token"])
+        # path = str(config["path"]) # not used
+    except TypeError:
+            print("Invalid configuration file.")
+            quit()
 
     client = AsyncClient(homeserver)
     client.access_token = token