event.data.indexOf is not a function in angular 2

Question

HTML Code:

<select class="form-select style-1 selectbox" sb="48771331" style="display: none;" formControlName="AutoID">
<option selected="0" value="0">---Select Country---</option>
<option *ngFor="let cd of countryData" value={{cd.AutoID}}>
{{cd.Name}}
</option>
</select>

Component.ts:

ngOnInit() {
debugger;
this.GetCountryList();
}
GetCountryList() {
this.loading = true;
this.schoolAddsService.GetCountryList()
.subscribe(data => {
this.loading = false;
this.countryData=data;
console.log(this.countryData);
},
error => {
console.log("Error :: " + error);
this.loading = false;
}
)
}

Service.ts:

export class SchoolAddsService{
constructor(private http: Http) { }
GetCountryList() {
return this.http.get(environment.apiPath + 'Country/GetCountries')
.map((res: Response) => res.json())
.catch(this.handleError)
}
private handleError(error: Response) {
return Observable.throw(error.statusText);
}
}