Func style allowing arrow (#461)

* eslint func-style rule added to server

* eslint func-style rule added to front-end

server/.eslintrc.js

@@ -21,5 +21,6 @@ module.exports = {
     '@typescript-eslint/explicit-function-return-type': 'off',
     '@typescript-eslint/explicit-module-boundary-types': 'off',
     '@typescript-eslint/no-explicit-any': 'off',
+    'func-style':['error', 'declaration', { 'allowArrowFunctions': true }],
   },
 };