Workflow configuration panel field "datetime-local" broken

[JamesUoM]

Opening a workflow with a datetime-local field through the following error in the browser console:

Uncaught TypeError: Cannot add property defaultValue, object is not extensible
    at workflowPanelUtils.ts:42:25
    at Array.forEach (<anonymous>)
    at fillDefaultConfig (workflowPanelUtils.ts:34:11)
    at workflowPanelUtils.ts:17:28
    at Array.forEach (<anonymous>)
    at setDefaultConfig (workflowPanelUtils.ts:15:15)
    at setDefaultValues (StartTaskWorkflowPage.tsx:54:32)
    at handleChange (StartTaskWorkflowPage.tsx:83:12)
    at onChange (DropDown.tsx:208:24)

I found this in 18.x but seems to be present in develop too.

[JamesUoM]

FieldSetField has defaultValue as an optional property so it should be assignable?

[JamesUoM]

removing the offending line seems to solve the issue:

diff --git a/src/utils/workflowPanelUtils.ts b/src/utils/workflowPanelUtils.ts
index 5d6dbf88..9d8c63c4 100644
--- a/src/utils/workflowPanelUtils.ts
+++ b/src/utils/workflowPanelUtils.ts
@@ -39,7 +39,6 @@ const fillDefaultConfig = (
     } else if (field.type === "datetime-local") {
       const date = new Date(new Date().toString().split("GMT")[0] + " UTC").toISOString().split(".")[0];
       defaultConfiguration[field.name] = date; // <-- this works to set the default
-      field.defaultValue = date;
     // set value in default configuration
     } else {
       defaultConfiguration[field.name] = field.value;