On Windows, start SB from the command line, with a non-existing fxml file as parameter :
$ ./scenebuilder.exe test.fxml

A popup error window appear. Close it.
Then, try to start SB from the Desktop icon : the tool do not start.

My use case is about launching SB from the IntelliJ IDE. In this case, the only way to deal with this is to kill the scenebuilder.exe process, as well as its associated javaw.exe.

Same issue with Linux. On Mac, one can restart SB without problem.
On Windows and Linux, we should exit the SB process when such an error appears.