De-installing the Extension gives an error with custom groups
When I disabled and then de-installed the Expenses extension, I can no longer access the custom groups/fields through Administer - Customise data and screens. I get an error (see attachment for the type of error).
What I did to solve is it to remove all custom groups and fields from the database. See also attachment.
After that, I could access the custom fields again.
Expense_extensions_-remove_custom_groups_and_custom_fields.odt