BuildStepList: Improve reporting on failed restore attempts

Change-Id: Icb402c4b489f1ff5fe18dd36872360f29234053a
Reviewed-by: hjk <hjk@qt.io>

src/plugins/projectexplorer/buildsteplist.cpp

@@ -130,7 +130,7 @@ bool BuildStepList::fromMap(const QVariantMap &map)
                 }
             }
         }
-        QTC_CHECK(handled);
+        QTC_ASSERT(handled, qDebug() << "No factory for build step" << stepId.toString() << "found.");
     }
     return true;
 }