Improve error message source. Add `build-list' Don't give internal error when inference returns a bad result. svn: r8885 original commit: f7d6b01d261521f8de4f572bd1b4644ea997dae2
svn: r8866 original commit: 5ff5d6c58005f8276e4517079ded454205359aba
svn: r8864 original commit: 0d54ed5e7427f5e75e6274cc3c9625e676fc34bc