tryReadTBQueueDefault: fix bug when returning Nothing
#707
| Job | Run time |
|---|---|
| 5m 3s | |
| 8m 17s | |
| 7m 37s | |
| 5m 6s | |
| 4m 17s | |
| 7m 47s | |
| 5m 39s | |
| 5m 22s | |
| 6m 42s | |
| 5m 13s | |
| 5m 16s | |
| 13m 46s | |
| 5m 20s | |
| 5m 19s | |
| 6m 48s | |
| 3m 14s | |
| 5m 50s | |
| 8m 12s | |
| 1h 54m 48s |