JavaFX – java.lang.nullpointer on one machine but not another

I have created a JavaFX Java program that displays few screens.
on one machine it works when I run from eclipse but fails when I run it as a jar.
on another machine it fails in eclipse with the same error I get previously.

I have linked a screenshot containing part of the code and also the error and folder layout.

any assistance is appreciated.

screenshot containing part of the code and also the error and folder layout

>Solution :

It looks like the fxml file you are trying to use is called MainForm.fxml. But on line 14 your are trying to use Mainform.fxml. Try capitalizing the ‘F’ on form.