无法以角度读取 Object.onClick 处的 null 属性“值”

Question

我想在查看按钮中查看上传的文件，但是当单击查看按钮时，错误显示为

无法读取 null 的属性“值” 在 Object.onClick

.component.ts

export class OnboardingProcessComponent implements OnInit {
//some code..
  measureDetailsForm = new FormGroup({});
  measureDetailsModel: any = {};
  measureDetailsOptions: FormlyFormOptions = {};
  {
          className:'flex-1',
          type: 'onboarding-file',
          key: 'PAS_20350_Certificate',
          templateOptions: {
            label: 'PAS 2030',
            change: (field, $event)=> {
              console.log($event);
              console.log(field);
            }
          },
          },
        {
           type: 'button',
           templateOptions: {
             //label: 'PAS 2030',
             text: 'VIEW',
             onClick: ($event) => {
              //  this.form.get('someInput').setValue('clicked!');
               this.openFile(this.measureDetailsForm.get('PAS_20350_Certificate').value)
             },
           },
},
 ngOnInit(): void {

}

openFile(fileUrl){
    window.open(fileUrl, '_blank')
  }

我使用了formly，所以我单独创建了按钮组件来创建按钮...

button-type.component.ts

import { Component } from '@angular/core';
import { FieldType } from '@ngx-formly/core';

@Component({
  selector: 'formly-field-button',
  template: `
    <div>
      <button [type]="to.type" class="lg-blue-button" (click)="onClick($event)">
        {{ to.text }}
      </button>
    </div>
  `,
})
export class FormlyFieldButton extends FieldType {
  onClick($event) {
    if (this.to.onClick) {
      this.to.onClick($event);
    }
  }
}