Add missing Mattermost::Error
Add missing Mattermost::Error

darkrasid/gitlabhq,axilleas/gitlabhq,iiet/iiet-git,openwide-java/gitlabhq,stoplightio/gitlabhq,htve/GitlabForChinese,axilleas/gitlabhq,LUMC/gitlabhq,iiet/iiet-git,mmkassem/gitlabhq,darkrasid/gitlabhq,htve/GitlabForChinese,jirutka/gitlabhq,t-zuehlsdorff/gitlabhq,t-zuehlsdorff/gitlabhq,htve/GitlabForChinese,iiet/iiet-git,t-zuehlsdorff/gitlabhq,dplarson/gitlabhq,dplarson/gitlabhq,mmkassem/gitlabhq,dplarson/gitlabhq,LUMC/gitlabhq,jirutka/gitlabhq,htve/GitlabForChinese,stoplightio/gitlabhq,darkrasid/gitlabhq,openwide-java/gitlabhq,LUMC/gitlabhq,LUMC/gitlabhq,t-zuehlsdorff/gitlabhq,stoplightio/gitlabhq,dreampet/gitlab,dreampet/gitlab,mmkassem/gitlabhq,iiet/iiet-git,stoplightio/gitlabhq,darkrasid/gitlabhq,jirutka/gitlabhq,dreampet/gitlab,mmkassem/gitlabhq,openwide-java/gitlabhq,jirutka/gitlabhq,axilleas/gitlabhq,dplarson/gitlabhq,dreampet/gitlab,openwide-java/gitlabhq,axilleas/gitlabhq