Add 404 error when no Excel found

app.py

@@ -282,6 +282,9 @@ def get_change_request_dataframe(req: DataRequest):
     soup = BeautifulSoup(resp.text, "html.parser")
     files = [item.get_text() for item in soup.select("tr td a")
              if item.get_text().endswith(".xlsx")]
+    
+    if files == []:
+        raise HTTPException(status_code=404, detail="No XLSX has been found")
 
     def gen_url(tdoc: str):
         return f"{url}/{tdoc}.zip"