This update resolves an issue where tax grouping keys in the account_edi_ubl module could sometimes be unexpectedly empty (None). This fix ensures accurate tax calculations and reporting, particularly when using customizations. Additionally, a minor correction was made regarding excise taxes.

Some overrides assign a value to the tax's grouping_key after the super call. However, the returned value could be None.

Also fix a little mistake regarding excise taxes.

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