Angular initializing form with @Input value becomes undefined on refresh

Question

I am passing a value from my parent component to my child component using the @Input() communication method. This value is used to initialize the form.

Parent Component.html

<child [someValue]="this.randomValue"></child>

Child Component.ts

@Input() someValue: any;

form: FormGroup;

ngOnInit(){
  this.form = this.fb.group(
    value: this.fb.array([someValue])
}

• someValue becomes undefined when page reloads... why?
• Is there a way to make sure it's not undefined?
• I tried to add this initialize the form in ngOnChanges which solves this problem however leads to unexpected results... such as it will always set the FormArray to this value and won't let additional values be added to the FormArray