fix: validate "null" value for point field as true when its not required (#12908)

### What?

This PR solves an issue with validation of the `point` field in Payload
CMS. If the value is `null` and the field is not required, the
validation will return `true` before trying to examine the contents of
the field

### Why?

If the point field is given a value, and saved, it is then impossible to
successfully "unset" the point field, either through the CMS UI or
through a hook like `beforeChange`. Trying to do so will throw this
error:

```
[17:09:41] ERROR: Cannot read properties of null (reading '0')
    err: {
      "type": "TypeError",
      "message": "Cannot read properties of null (reading '0')",
      "stack":
          TypeError: Cannot read properties of null (reading '0')
              at point (webpack-internal:///(rsc)/./node_modules/.pnpm/payload@3.43.0_graphql@16.10.0_typescript@5.7.3/node_modules/payload/dist/fields/validations.js:622:40)
```

because a value of `null` will not be changed to the default value of
`['','']`, which in any case does not pass MongoDB validation either.

```
[17:22:49] ERROR: Cast to [Number] failed for value "[ NaN, NaN ]" (type string) at path "location.coordinates.0" because of "CastError"
    err: {
      "type": "CastError",
      "message": "Cast to [Number] failed for value \"[ NaN, NaN ]\" (type string) at path \"location.coordinates.0\" because of \"CastError\"",
      "stack":
          CastError: Cast to [Number] failed for value "[ NaN, NaN ]" (type string) at path "location.coordinates.0" because of "CastError"
              at SchemaArray.cast (webpack-internal:///(rsc)/./node_modules/.pnpm/mongoose@8.15.1_@aws-sdk+credential-providers@3.778.0/node_modules/mongoose/lib/schema/array.js:414:15)
```


### How?

This adds a check to the top of the `point` validation function and
returns early before trying to examine the contents of the point field

---------

Co-authored-by: Dave Ryan <dmr@Daves-MacBook-Pro.local>

Author: dave-wwg

packages/payload/src/fields/validations.ts

@@ -937,19 +937,27 @@ export type PointFieldValidation = Validate<
 >
 
 export const point: PointFieldValidation = (value = ['', ''], { req: { t }, required }) => {
-  const lng = parseFloat(String(value![0]))
-  const lat = parseFloat(String(value![1]))
+  if (value === null) {
+    if (required) {
+      return t('validation:required')
+    }
+
+    return true
+  }
+
+  const lng = parseFloat(String(value[0]))
+  const lat = parseFloat(String(value[1]))
   if (
     required &&
-    ((value![0] && value![1] && typeof lng !== 'number' && typeof lat !== 'number') ||
+    ((value[0] && value[1] && typeof lng !== 'number' && typeof lat !== 'number') ||
       Number.isNaN(lng) ||
       Number.isNaN(lat) ||
       (Array.isArray(value) && value.length !== 2))
   ) {
     return t('validation:requiresTwoNumbers')
   }
 
-  if ((value![1] && Number.isNaN(lng)) || (value![0] && Number.isNaN(lat))) {
+  if ((value[1] && Number.isNaN(lng)) || (value[0] && Number.isNaN(lat))) {
     return t('validation:invalidInput')
   }
 

test/fields/int.spec.ts

@@ -1396,6 +1396,58 @@ describe('Fields', () => {
       expect(doc.localized).toEqual(localized)
       expect(doc.group).toMatchObject(group)
     })
+
+    it('should throw validation error when "required" field is set to null', async () => {
+      if (payload.db.name === 'sqlite') {
+        return
+      }
+      // first create the point field
+      doc = await payload.create({
+        collection: 'point-fields',
+        data: {
+          localized,
+          point,
+        },
+      })
+
+      // try to update the required field to null
+      await expect(() =>
+        payload.update({
+          collection: 'point-fields',
+          data: {
+            point: null,
+          },
+          id: doc.id,
+        }),
+      ).rejects.toThrow('The following field is invalid: Location')
+    })
+
+    it('should not throw validation error when non-"required" field is set to null', async () => {
+      if (payload.db.name === 'sqlite') {
+        return
+      }
+      // first create the point field
+      doc = await payload.create({
+        collection: 'point-fields',
+        data: {
+          localized,
+          point,
+        },
+      })
+
+      expect(doc.localized).toEqual(localized)
+
+      // try to update the non-required field to null
+      const updatedDoc = await payload.update({
+        collection: 'point-fields',
+        data: {
+          localized: null,
+        },
+        id: doc.id,
+      })
+
+      expect(updatedDoc.localized).toEqual(undefined)
+    })
   })
 
   describe('checkbox', () => {