Ionic Validation Array Form - ionic-framework

Question

I have the below form that is generate dynamically, I am trying to make a validation but is fail
Error: ExpressionChangedAfterItHasBeenCheckedError: Expression has changed after it was checked. Previous value: 'model: sdaDAd'. Current value: 'model: '.
HTML
<div [formGroup]="someForm">
<ion-item-group *ngFor="let att of day; let idx = index">
<ion-item >
<ion-label color="primary">{{att.label}}{{idx+1}}. Day</ion-
label>
<ion-input formControlName="day" type="text" text-right
[(ngModel)]="day[idx].value"></ion-input>
</ion-item>
<ion-item >
<ion-label color="primary">{{att.label}}{{idx+1}}. Exc</ion-label>
<ion-input type="text" formControlName="exc" text-right
[(ngModel)]="exc[idx].value"></ion-input>
</ion-item>
<ion-item >
<ion-label color="primary">{{att.label}}{{idx+1}}.
Hint/Repeats</ion-label>
<ion-input type="text" formControlName="hint" text-right
[(ngModel)]="hint[idx].value"></ion-input>
</ion-item>
<span color=danger float-right ion-button icon-left clear
*ngIf="exc.length > 0"
(click)="removeInputField(idx)"><ion-icon name="close"></ion-icon>
Remove
</span>
</ion-item-group>
<ion-card *ngIf="data_exc">
<ion-item *ngFor="let att of exc; let i=index">
<div class="card-title">Exc: {{att.value}}</div>
<div class="card-title">Hint/Repeats: {{hint[i].value}}</div>
<div class="card-title">Day: {{day[i].value}}</div>
</ion-item>
<div class="card-title">Notes: {{workoutData.notes}}</div>
</ion-card>
<button ion-button (click)="Add()">+Add</button>
<button ion-button (click)="goTo()" >Preview</button> <br>
<ion-toolbar>
<ion-item>
<ion-textarea placeholder="Tap here to enter a new note"
[(ngModel)]="workoutData.notes" formControlName="notes"
autocomplete="on" autocorrect="on"></ion-textarea>
</ion-item>
</ion-toolbar>
<button [disabled]="!someForm.valid" ion-button full
(click)="presentConfirmCustomWorkout()" type="submit" >Submit</button>
</div>
Validation to check if the form is empty so I will not get empty values in array
this.someForm = formbuilder.group({
'day': [this.day.value, Validators.compose([Validators.required])],
'exc': [this.exc.value, Validators.compose([Validators.required])],
'hint': [this.hint.value, Validators.compose([Validators.required])],
'notes': ['', Validators.compose([Validators.required])],
});