fix(ui): properly differentiate between DOM events and raw values in setValue (#12892)

Because of this check, if a JSON with a property `target` was saved it
would become malformed.

For example trying to save a JSON field:

```json
{
  "target": {
    "value": {
      "foo": "bar"
    }
  }
}
```

would result in:

```json
{
  "foo": "bar"
}
```

And trying to save:

```json
{
  "target": "foo"
}
```

would just not save anything:

```json
null
```

I went through all of the field types and did not find a single one that
would rely on this ternary. Seems like it always defaulted to `const val
= e`, except the unexpected case described previously.

Fixes #12873

Added test may be overkill, will remove if so.




---
- To see the specific tasks where the Asana app for GitHub is being
used, see below:
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---------

Co-authored-by: Jacob Fletcher <jacobsfletch@gmail.com>

packages/ui/src/forms/useField/index.tsx

@@ -77,7 +77,17 @@ export const useField = <TValue,>(options?: Options): FieldType<TValue> => {
   // update field values from field component(s)
   const setValue = useCallback(
     (e, disableModifyingForm = false) => {
-      const val = e && e.target ? e.target.value : e
+      // TODO:
+      // There are no built-in fields that pass events into `e`.
+      // Remove this check in the next major version.
+      const isEvent =
+        e &&
+        typeof e === 'object' &&
+        typeof e.preventDefault === 'function' &&
+        typeof e.stopPropagation === 'function'
+
+      const val = isEvent ? e.target.value : e
+
       dispatchField({
         type: 'UPDATE',
         disableFormData: disableFormData || (hasRows && val > 0),

test/fields/collections/JSON/e2e.spec.ts

@@ -102,6 +102,21 @@ describe('JSON', () => {
     )
   })
 
+  test('should save field with "target" property', async () => {
+    const input = '{"target": "foo"}'
+    await page.goto(url.create)
+    const jsonCodeEditor = page.locator('.json-field .code-editor').first()
+    await expect(() => expect(jsonCodeEditor).toBeVisible()).toPass({
+      timeout: POLL_TOPASS_TIMEOUT,
+    })
+    const jsonFieldInputArea = page.locator('.json-field .inputarea').first()
+    await jsonFieldInputArea.fill(input)
+
+    await saveDocAndAssert(page)
+    const jsonField = page.locator('.json-field').first()
+    await expect(jsonField).toContainText('"target": "foo"')
+  })
+
   test('should update', async () => {
     const createdDoc = await payload.create({
       collection: 'json-fields',