eslint issue fix(?)

Author: jamesdoh0109

frontend/plan/package.json

@@ -55,6 +55,7 @@
   },
   "devDependencies": {
     "@types/leaflet": "^1.9.14",
+    "eslint": "^9.14.0",
     "eslint-config-airbnb": "^17.1.1",
     "eslint-config-prettier": "^6.11.0",
     "eslint-plugin-flowtype": "^4.7.0",