FE: KC: Fix no error is displayed if the syntax is not valid (#3750)

Co-authored-by: Roman Zabaluev <rzabaluev@provectus.com>

kafka-ui-react-app/src/components/Connect/Details/Config/Config.tsx

@@ -37,7 +37,7 @@ const Config: React.FC = () => {
     formState: { isDirty, isSubmitting, isValid, errors },
     setValue,
   } = useForm<FormValues>({
-    mode: 'onTouched',
+    mode: 'onChange',
     resolver: yupResolver(validationSchema),
     defaultValues: {
       config: JSON.stringify(config, null, '\t'),