if job chains are used improperly we can end up with jobs with nil fu…

…nctions (#388)

* if job chains are used improperly we can end up with jobs with nil functions

* Update executor.go

* Update executor.go

executor.go

@@ -47,6 +47,8 @@ func (e *executor) start() {
 		case f := <-e.jobFunctions:
 			runningJobsWg.Add(1)
 			go func() {
+				defer runningJobsWg.Done()
+
 				panicHandlerMutex.RLock()
 				defer panicHandlerMutex.RUnlock()
 
@@ -58,8 +60,6 @@ func (e *executor) start() {
 					}()
 				}
 
-				defer runningJobsWg.Done()
-
 				if e.maxRunningJobs != nil {
 					if !e.maxRunningJobs.TryAcquire(1) {
 

scheduler.go

@@ -545,6 +545,13 @@ func (s *Scheduler) run(job *Job) {
 	}
 
 	job.mu.Lock()
+
+	if job.function == nil {
+		job.mu.Unlock()
+		s.Remove(job)
+		return
+	}
+
 	defer job.mu.Unlock()
 
 	if job.runWithDetails {