I will assume that you are using the 4.x version of the API since it seems `GeoJSONLayer` was implemented in 4.11.

Remember that you have to define the modules and classes you will use on top of your script. I see you are calling several modules and classes but `GeoJsonLayer` is not listed (hence the error you are getting). If you take a look at the [documentation][1], you will see that you need to integrate the following piece of code:

```
require(["esri/layers/GeoJSONLayer"], function(GeoJSONLayer) { /* code goes here */ });
```

Also, note that it is `GeoJSONLayer` and not `GeoJsonLayer` (althought you could name it anything you wanted inside `function()`).

  [1]: https://developers.arcgis.com/javascript/latest/api-reference/esri-layers-GeoJSONLayer.html