Accessing FormArray content for validation but receives null or undefined error

HTML

<form [formGroup]="newMovieForm">
   <ng-container formArrayName="actors">
     <ng-container *ngFor="let actor of (actors['controls'] || []) ; let i = index">
        <div [formGroupName]="i">  
            <input type="text" class="form-control" placeholder="First Name" formControlName="firstName" required>
                 <span *ngIf="newMovieForm.controls['actors']?.get(i).controls['firstName'].errors?.['hasSpaces']">class="text-danger">
                     Field is required!
                </span>

TS Main Form Group

this.newMovieForm = this.fb.group({
      // This are known as controls
      movieName: ['', [Validators.required, CustomValidators.noSpaceAllowed]],
      yearOfRelease: ['', [Validators.required]],
      description: ['', [Validators.required]],
      rentalCost: ['', [Validators.required, CustomValidators.onlyNumbersAllowed]],
      imageUrl: ['', [Validators.required, CustomValidators.noSpaceAllowed]],
      actors: this.fb.array([]),
      userReviews: this.fb.array([])
    })

TS Add-on Form Group

addActor() {
    const actor = this.fb.group({
      firstName: ['', [Validators.required, CustomValidators.noSpaceAllowed]],
      lastName: ['', [Validators.required, CustomValidators.noSpaceAllowed]],
      gender: ['', [Validators.required]],
      age: ['', [Validators.required]],
      imageUrl: ['', [Validators.required, CustomValidators.noSpaceAllowed]]
    });
    this.actors.push(actor);
  }

I am try to access the firstName.validators of the actor formGroup so I can display a specific error if the user does not fulfil certain criteria. I am confused about two things:

*ngIf="newMovieForm.controls['actors']?.get(i).controls['firstName'].errors?.['hasSpaces']

1. I am not sure if the above statement is correct in checking if the specific field is valid

2. If the above statement is correct. I can’t seem to get rid of the Object is possibly "null" or "undefined" despite using ? or null checks like

*ngIf=" i !== null && i ! == undefined"

I do not wish to turn off strict mode, is there a way i can fix this issue.

>Solution :

<ng-container formArrayName="actors">
 <ng-container *ngFor="let actor of (actors['controls'] || []) ; let i = index">
    <div [formGroupName]="i">  
        <input type="text" class="form-control" placeholder="First Name" formControlName="firstName" required>
             <span *ngIf="newMovieForm.hasError('hasSpaces','actors.'+i+'.firstName')">class="text-danger">
                 Field is required!
            </span>