My coworker was using a custom primary key like so:
```
User sql=users
    Id sqltype=uuid default=uuid_generate_v4
    email Email sqltype=text
    UniqueEmail email
    createdAt UTCTime
    modifiedAt UTCTime
    deriving Show Eq Typeable
```
But didn't specify the type of the Id to be UUID. This caused Persistent to expect an Int64, leading to a very confusing error message on insert:
```
*** Exception: runFakeHandler issue: InternalError "Invalid result from a SQL insert, got: [PersistDbSpecific \"70c2418d-fb00-43f7-818d-eaf962612030\"]
```
By providing the actual underlying error, it gets much clearer:
```
*** Exception: runFakeHandler issue: InternalError "Invalid result from a SQL insert, got: [PersistDbSpecific \"70c2418d-fb00-43f7-818d-eaf962612030\"]. Error was: \"int64 Expected Integer, received: PersistDbSpecific \\\"70c2418d-fb00-43f7-818d-eaf962612030\\\"\"
```