fixed undefined instance error
fixed undefined instance error

I got an error using the features id, since ngOnChange seemed to be fired before ngOnInit and due to this instance being undefined.
karomamczi/ngx-openlayers,karomamczi/ngx-openlayers,quentin-ol/ngx-openlayers,quentin-ol/ngx-openlayers,karomamczi/ngx-openlayers,quentin-ol/ngx-openlayers