ERROR TypeError: Cannot read property 'hasError' of undefined

Hi I am facing this below error for the code I have pasted . My angular version is 7.24.

core.js:15724 ERROR TypeError: Cannot read property 'hasError' of undefined

at CustomerComponent.push../src/CustomerApp/Customer/CustomerApp.component.ts.CustomerComponent.hasError (CustomerApp.component.ts:29)

at Object.eval [as updateRenderer] (CustomerComponent.ngfactory.js:11)

at Object.updateRenderer (core.js:23656)

at checkAndUpdateView (core.js:23312)

at callViewAction (core.js:23548)

at execEmbeddedViewsAction (core.js:23511)

at checkAndUpdateView (core.js:23308)

at callViewAction (core.js:23548)

at execComponentViewsAction (core.js:23490)

at checkAndUpdateView (core.js:23313)

hasError(typeOfValidator: string, controlName: string): boolean {

    console.log("hi inside code.")

    return  this.CustomerModel

                .customerFormGroup

                .contains[controlName]

                .hasError(typeOfValidator);

  }