[#3191] added client-side validation and syntax highlight for the json field

ui/package.json

@@ -18,6 +18,7 @@
     "@codemirror/lang-html": "^6.1.0",
     "@codemirror/lang-javascript": "^6.0.2",
     "@codemirror/lang-sql": "^6.4.0",
+    "@codemirror/lang-json": "^6.0.0",
     "@codemirror/language": "^6.0.0",
     "@codemirror/legacy-modes": "^6.0.0",
     "@codemirror/search": "^6.0.0",