GDPR field lists crashes when subsciption module is enabled

Problem/Motivation

If there is subscription module enabled and used in several places for users to subscribe to certain context, then if we install the GDPR module and try to access the gdpr field list then it encounters unexpected problem, Deleting the subscription module allows the user to access the field list.

Steps to reproduce

Enable subscription module , Enable GDPR module. Go to /reports/fields/permissions//gdpr-fields to observe the error. To solve the issue only way is to delete the subscription module or disable the module and enable another subscription module (which currently doesn't exist)