Install-script default is broken

[Jojodicus]

when using the install script and not selecting an install option (i.e. using the default) the script behaves unexpectedly

console output:

$ ./install.sh
Please select an option for presets installation (Default=1)
1) Install all presets
2) Install Perfect EQ preset
3) Install all bass boosting presets
4) Install Advanced Auto Gain
5) Install Laptop speaker preset

environment: line 28: [: : integer expression expected
environment: line 28: [: : integer expression expected