Angular: how to fix this Type 'Customer | undefined 'is not assignable to type' Customer '

I am experiencing this error. This is code:

...
export class ListCustomersComponent implements OnInit {

  customers: Array<Customer> = [];
  showCustomer?: Customer;
  isSelected: boolean = false;
  deletedCustomer?: Customer;
  returnedMessage?: string;

  constructor(private customerService: CustomerService,
                private messageService: MessageService) { }

     
  updateCustomer() {
    this.customerService.updateCustomer(this.showCustomer!)
                      .subscribe((message: Message) => {
                        console.log(message);
                        // update customers list
                        this.customers.map(x => {
                          if(x.id == this.showCustomer!.id){
            ERROR------>    x = this.showCustomer;
                          }
                        });

                        
  }

The error is in updateCustomer() to the line x = this.showCustomer;. How can I fix it? Thank you all

Typescript is giving a warning that the value may be undefined. An exclamation point ignores that warning. This is fine if your logic ensures that there will be a value. If there isn't a value x will be set to undefined.

To ignore the warning for this case you have to add an exclamation mark for the x = this.showCustomer statement. By using ! typescript marks it as present.

   this.customerService.updateCustomer(this.showCustomer!)
                      .subscribe((message: Message) => {
                        console.log(message);
                        // update customers list
                        this.customers.map(x => {
                          if(x.id == this.showCustomer!.id){
                             x = this.showCustomer!; // Added ! after showCustomer
                          }
                        });

Explanation ! in docs