Clearing a Field ?

I have a field like this

```
@Field(() => GraphQLJSONObject || [], { nullable: true })
@Column({ type: 'jsonb', nullable: true })
externalLinks: [{ title: string; url: string }];
```
it doesn't like it in typescript if I try to clear this field.... 

ie

```
foo.externalLinks = []
```
or 
```
foo.externalLinks = null
```