tslint / codelyzer / ng lint error: “for (… in …) statements must be filtered with an if statement”

Question

Lint error message:

src/app/detail/edit/edit.component.ts[111, 5]: for (... in ...) statements must be filtered with an if statement

Answer 1

for (const field in this.formErrors) {
  if (this.formErrors.hasOwnProperty(field)) {

for (const key in control.errors) {
  if (control.errors.hasOwnProperty(key)) {