jams-react-client: add checkJs compiler flag

Change-Id: I9f9f0ace1fd95773ce4a680f47a070884d0e3502

jams-react-client/.eslintrc.js

@@ -20,5 +20,6 @@ module.exports = {
   ],
   rules: {
     "react/prop-types": "off",
+    "no-unused-vars": "warn",
   },
 };

jams-react-client/jsconfig.json

 {
   "compilerOptions": {
+    "jsx": "react",
     "baseUrl": "src",
     "paths": {
       "*": ["./src/*"]
-    }
+    },
+    "checkJs": true
   }
 }