[BUG] Chaincode returns 500 error instead of 400 in some cases

[samlesu]

Describe the bug
The chaincode responds in some cases a 500 error instead of a 400 error. For traceability and debugging it should be fixed: 500 errors are server errors and 400 errors are user errors.

Investigation

This is at least true for the following error:

            return Permissions{}, fmt.Errorf("invalid permission input values")

We should go through all the errors returned by the chaincode and ensured they have the proper status code.