Fix undefined check

[marr]

Description

Dropdown was throwing because it was trying to invoke a method on M when M was undefined. Components don't work as expected without the M global defined. This should be added to the documentation:

window.M = require('materialize-css')

Without that, things like dropdowns don't work.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

[alextrastero]

We're actually trying to remove the check of typeof M undefined, since with this check it will fail in silence.

I would rather an error come up and knowing where to fix.

As per the documentation, it clearly states to add path/to/materialize.js before the bundle.

Of course an example for adding materialize to the current bundle as an es module would be great.

[alextrastero]

Thanks for the contribution!