angular default value in option tag code example
Example 1: in select option how to make one default in angular
<option [ngValue]="undefined" selected>Select</option>
Example 2: set default value in dropdown angular 7
Set validation.min with required as well like below one.
supplierId: ["", [Validators.required, Validators.min(1)]]
supplierId is always greater zero so min(1) works for you.