adding a name to a PGP key causes "General error"

Adding the user `Karl-Philipp Richter` with E-Mail `...@posteo.de` causes an error message `Couldn't add user id` with only content `General error`. Unfortunately such error message (why ever someone ever put it in the code) don't allow any further investigation of the problem. I'd suggest a code review of when this message occurs. Important to stress is that such a message should NEVER be displayed. Every error has a cause which MUST be revealed to the user.

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: seahorse 3.12.2-1ubuntu1
Uname: Linux 3.17.6-031706-generic x86_64
NonfreeKernelModules: zfs zunicode zcommon znvpair zavl spl
ApportVersion: 2.14.7-0ubuntu8
Architecture: amd64
CurrentDesktop: Unity
Date: Tue Dec 9 08:11:56 2014
SourcePackage: seahorse
UpgradeStatus: No upgrade log present (probably fresh install)