Uninstalling the module causes text widget's to be inaccessible

Hi,

A few moments ago I uninstalled this module on a test site because the module was giving me errors after creating a node.
The error I got:

Column 'field_bestel_btw_vat' cannot be null query: INSERT INTO amu6_content_type_bestelling (...) VALUES (...) in /.../sites/all/modules/cck/content.module on line 1213.

Because this wasn't such a priority to have validation I thought "I'll replace it with a simple text field". After disabling and uninstalling the module though I notice my other text fields are missing when creating a new node. On the "Manage fields" page I got following errors:

This content type has inactive fields. Inactive fields are not included in lists of available fields until their modules are enabled.

And following notices:

    * Voornaam (field_bestel_vnaam) is an inactive Text field that uses a Text field widget.
    * Achternaam (field_bestel_fnaam) is an inactive Text field that uses a Text field widget.
    * Facturatie naam (field_bestel_fact_naam) is an inactive Text field that uses a Text field widget.
    * BTW nummer (field_bestel_btw) is an inactive Text field that uses a Text field widget.
    * BTW nummer test (field_vat_test) is an inactive vat field that uses a Text field widget.

I'll activate the module in the mean time so my content-types aren't lost but is there a possibility to make a patch so I can safely remove the module?

Thanks a lot in advance,
Hatznie.