Fix modalWidthClass and add Exception

[PhiloNL]

Make sure the class is applied and throw an exception if chosen width is undefined.

[Christophvh]

@PhiloNL This change made all our modals very small. Yet I still have 2xl in my config file. Does that mean i need to switch to 3xl and this was not working before or?

[PhiloNL]

@Christophvh it might has to do with the whitelisting of the class, if you add these to your Tailwind config it should work as nothing has changed:

module.exports = {

    content: [
        './vendor/wire-elements/modal/**/*.blade.php',
    ],

    safelist: [
        "sm:max-w-sm",
        "sm:max-w-md",
        "sm:max-w-lg",
        "sm:max-w-xl",
        "sm:max-w-2xl",
        "sm:max-w-3xl",
        "sm:max-w-4xl",
        "sm:max-w-5xl",
        "sm:max-w-6xl",
        "sm:max-w-7xl"
    ],

};

[Christophvh]

I already had the one we use which is the default here. I tried with all these but the same result. I also found this PR that seems to change how max-width works but we only published the config file, not the stylesheets. #111

The only thing that works is changing the default to 3xl instead of 2xl which seems strange.

[PhiloNL]

Are you using the include_css option? Can you verify the 2xl class has CSS applied when you inspect the modal with your browser developer tools? Also, which version of Tailwind are you using?