fix: gender and previous state for DEMO

cutt/main.py

@@ -114,7 +114,7 @@ def get_mvps(
             return mvps
         else:
             raise HTTPException(
-                status_code=status.HTTP_404_NOT_FOUND,
+                status_code=status.HTTP_400_BAD_REQUEST,
                 detail="no previous state was found",
             )
 
@@ -158,11 +158,11 @@ def get_chemistry(
             subquery, (C.user == subquery.c.user) & (C.time == subquery.c.latest)
         )
         chemistry = session.exec(statement2).one_or_none()
-        if chemistry:
+        if chemistry is not None:
             return chemistry
         else:
             raise HTTPException(
-                status_code=status.HTTP_404_NOT_FOUND,
+                status_code=status.HTTP_400_BAD_REQUEST,
                 detail="no previous state was found",
             )