Hi Simon,
it seems like the domain model was changed by adding a (unique) index. However, when starting the application it checks if the existing data is already unique (and if not, it will fail to create the index).
This does not happen on acceptance/test as there the data was unique.
To resolve, you first need to remove any duplicate values from the target entity/attribute combination (error message mentions the index uniq_xtools$user_email and attribute email), only then you can deploy your new code with the unique index