DevForce Code First build time support does detect a number of mapping issues early, which you wouldn't normally see until run time.  But there's always room for improvement. 

We are experiencing difficulty most of the time when we try to use our Code First Model that has a minor mismatch of Schema in the database. 

(E.g. in Model the field is nullable and in the Database it is not)

What I mean is to say is that, we can successfully build our project and the ibmx file is updated but when using the actual model to query or by simply instantiating it, a weird error occurs.

The problem here is that there is no "Friendly Error Message" being thrown during build time or runtime that can easily help the developers to pinpoint the issue.

Are there some configuration that we need to consider or something that might help us?

Thanks,

Von