worker/server: set a job error when heartbeat gets missing

Previously, we just used an empty struct when heartbeat failed. This is fine
for the osbuild job because it's treated as a failed one when
result.OSBuildResult == false which is the default value.

koji-finalize works differently though: It's in a failed state if there's
an job error of kojiError != "". So when failed heartbeat set the struct to
be empty, this was treated as success because there's no error.

Let's fix this by introducing a new error for the situation where we don't get
a heartbeat in time for a specific job.

internal/worker/clienterrors/errors.go

@@ -27,6 +27,7 @@ const (
 	ErrorEmptyPackageSpecs    ClientErrorCode = 24
 	ErrorDNFRepoError         ClientErrorCode = 25
 	ErrorJobDependency        ClientErrorCode = 26
+	ErrorJobMissingHeartbeat  ClientErrorCode = 27
 )
 
 type ClientErrorCode int

internal/worker/server.go

@@ -100,7 +100,17 @@ func (s *Server) WatchHeartbeats() {
 		for _, token := range s.jobs.Heartbeats(time.Second * 120) {
 			id, _ := s.jobs.IdFromToken(token)
 			logrus.Infof("Removing unresponsive job: %s\n", id)
-			err := s.FinishJob(token, nil)
+
+			missingHeartbeatResult := JobResult{
+				JobError: clienterrors.WorkerClientError(clienterrors.ErrorJobMissingHeartbeat, "Worker running this job stopped responding."),
+			}
+
+			resJson, err := json.Marshal(missingHeartbeatResult)
+			if err != nil {
+				logrus.Panicf("Cannot marshal the heartbeat error: %v", err)
+			}
+
+			err = s.FinishJob(token, resJson)
 			if err != nil {
 				logrus.Errorf("Error finishing unresponsive job: %v", err)
 			}