Trying to debug a snap for Electricsheep

I am trying to make a snap for Electricsheep,

It is also possible to install/test on Ubuntu using this tutorial, (creates a .deb file using checkinstall, but it is not a deb file to put in repositories).

I have come up with this snapcraft.yaml,
The snapcraft.yaml manages to create the .snap file.
However, when I run the program “electricsheep”, I get a black fullscreen, and in the middle there is a white box.

What should be next step be in order to figure out the issue?