upd plot context on job deletion

GUI/Model/Job/JobsSet.cpp

@@ -130,6 +130,7 @@ void JobsSet::removeJob(JobItem* job_item)
     ASSERT(job_item);
     job_item->haltWorker();
     delete_element(job_item);
+    emit jobMeritsAttention(nullptr);
 }
 
 bool JobsSet::hasUnfinishedJobs() const