Currently, the donation and membership forms don't handle a server roundtrip with invalid data well. We rely on the client-side code to be so good that server-side validation errors don't occur. However, we have no idea if the client always sends valid data. As a first step of rectifying this, we need to log server-side validation failure of form submits.
- Whenever the input validation in the controller of donation/add or apply-for-membership fails, log the validation error and the posted data as a WARNING