Need to determine if an action is being called by the admin site (is_admin?)

Hi

I am developing my very first plug-in which is extremely simple and yet I have managed to bugger it up ??

I have hooked wp_head so I can insert a new script tag into every page header and it works for the main site but when the plugin is activated on the admin side I get an error telling me the

Now, I dont actually want the script included for admin pages so what I would like is some sort of function like is_admin() but i have searched this page (https://codex.www.ads-software.com/Conditional_Tags) and there seems to be nothing.

Thanks in advance

The full code for my plug in is below for reference:

add_action(‘wp_head’, ‘add_mint_javascript’);

function add_script($unused) {
echo ‘<script src=”/my.js” type=”text/javascript”></script>’;
}