Description :

When you open the Launcher firestorm, it closes directly or displays an error message.

Solution:

Open the Terminal

Open "FirestormLauncher" with a right click, and select the option "Show package contents".

Open the Contents/MacOS folder

Type in the Terminal the command "chmod u+x" (space is important)

Select in the MacOS folder, "FirestormLauncher", and drop it in the terminal

The final command should look like this: "chmod u+x /Applications/FirestormLauncher/FirestormLauncher.app/Contents/MacOS/FirestormLauncher"

Press ENTER, and if no errors are displayed, you can launch the Firestorm Launcher without any problems.