improve responses

app/__init__.py

@@ -2,7 +2,7 @@ from flask import Flask
 from flask_cors import CORS
 from app.config import Config
 from app.routes import auth_bp, autocall_bp
-from app.errors import method_not_allowed, unsupported_media_type
+from app.response import (method_not_allowed, unsupported_media_type, not_found, bad_request)
 from app.extensions import db
 
 
@@ -23,6 +23,8 @@ def create_app():
     # Error Handlers
     app.register_error_handler(405, method_not_allowed)
     app.register_error_handler(415, unsupported_media_type)
+    app.register_error_handler(404, not_found)
+    app.register_error_handler(400, bad_request)
 
     # Database
     db.init_app(app)