TextDataGroup behavior should match behavior of StringCell

src/components/DataGroups/TextDataGroup.js

@@ -1,10 +1,17 @@
-const valueToString = (value) => {
+import { format, isValid } from "date-fns";
+import { dateTimeFormat } from "../CellViews/DateTimeCell";
+
+export const valueToString = (value) => {
   if (typeof value === "string") return value;
+  /* if undefined or null we'll treat it as empty string */
+  if (value === undefined || value === null) return "";
+  if (value instanceof Date && isValid(value)) return format(value, dateTimeFormat);
 
   try {
+    /* JSON.stringify will handle JSON and non-strings, non-null, non-undefined */
     return JSON.stringify(value);
   } catch {
-    return (value ?? "").toString();
+    return 'Error: Invalid JSON';
   }
 };