Trigger ItemFinished when temp file creation fails instead of failing silently

internal/events/events.go

@@ -258,3 +258,14 @@ func (s *BufferedSubscription) Since(id int, into []Event) []Event {
 
 	return into
 }
+
+// Error returns a string pointer suitable for JSON marshalling errors. It
+// retains the "null on sucess" semantics, but ensures the error result is a
+// string regardless of the underlying concrete error type.
+func Error(err error) *string {
+	if err == nil {
+		return nil
+	}
+	str := err.Error()
+	return &str
+}