.gitignore

+# Local
+.vscode
+
 # Byte-compiled / optimized / DLL files
 __pycache__/
 *.py[cod]

Files-API/files_api.py

 import os
-from flask import Flask, send_from_directory, jsonify
+from flask import Flask, send_from_directory, jsonify, current_app
 from flask_cors import CORS, cross_origin
 
 
 @cross_origin(origin="localhost", headers=["Content-Type", "Authorization"])
 def list_files():
     files = list()
-    for filename in os.listdir("articles"):
-        path = os.path.join("articles", filename)
+    for filename in os.listdir(os.path.join(current_app.root_path, "articles")):
+        path = os.path.join(current_app.root_path, "articles", filename)
         if os.path.isfile(path):
             files.append(filename)
     return jsonify(files)