Set Error for Nested Object

[fadi-george]

I have some field that looks like:

{
  someField: {
    [SomeName1: string]: {
       Label1: string;
       Label2: ....; 
    },
    [SomeName2: string]: {
       Label1: string;
       Label2: ....; 
    },
    ...
  } 
}

Id either want to set 1 error for the whole group or some of nested prop e.g.
setError('someField', { type: 'custom', message: 'some message'}); or
setError('someField', { type: 'custom.someName1', message: 'some message'});

but typescript will complain e.g.

  const someFieldErrs = formState.errors.someField;
  const someFieldErr = someFieldErrs ? someFieldErrs[Object.keys(someFieldErrs)[0]]?.message : null; // FieldError or null or undefined
 // but want it to be string or undefined