[MSHARED-337] don't check canGenerateReport() since it is part of report generation, not execution/preparation

git-svn-id: https://svn.apache.org/repos/asf/maven/shared/trunk@1595572 13f79535-47bb-0310-9956-ffa450edef68
[MSHARED-333] improved message

git-svn-id: https://svn.apache.org/repos/asf/maven/shared/trunk@1595577 13f79535-47bb-0310-9956-ffa450edef68