Can't save opened files on linux

[Miner34dev]

Steps to reproduce:

• Open nodesnap
• Click open file
• Choose a .truck file
• Do something (add a node, create a new beam etc...)
• Click edit -> save
• Close nodesnap
• Open your .truck file in a text editor
• You will see that the file is still untouched

This is pretty bad, as i have to save everything manually with a text editor, which makes this pretty much unuseful.
Note: Every time i create a project it says Failed to save project preferences! Invalid path.