Fix worker crash when first heartbeat conflicts with job start
```
INFO: 2024-02-27 21:49:47,093 - root - [config-split-names] compute JobManager(job_id=65de58fa62c68c8c749fbce3 dataset=ChristophSchuhmann/queries job_info={'job_id': '65de58fa62c68c8c749fbce3', 'type': 'config-split-names', 'params': {'dataset': 'ChristophSchuhmann/queries', 'revision': '641561f9b27193174a37e5a57ffbe258e997ffba', 'config': 'default', 'split': None}, 'priority': <Priority.NORMAL: 'normal'>, 'difficulty': 60}
INFO: 2024-02-27 21:49:47,103 - root - compute 'config-split-names' from config-info for dataset='ChristophSchuhmann/queries' config='default'
INFO: 2024-02-27 21:49:47,105 - root - Cannot compute 'config-split-names' from config-info for self.dataset='ChristophSchuhmann/queries' self.config='default'. Trying to compute it using streaming.
INFO: 2024-02-27 21:49:47,105 - root - compute 'config-split-names' using streaming for dataset='ChristophSchuhmann/queries' config='default'
WARNING: 2024-02-27 21:49:57,009 - root - Heartbeat failed for job 65de58fa62c68c8c749fbce3: JobDocument matching query does not exist.
INFO:     Shutting down
INFO:     Waiting for application shutdown.
INFO:     Application shutdown complete.
INFO:     Finished server process [56]
```
Fix worker crash when first heartbeat conflicts with job start: ```
INFO: 2024-02-27 21:49:47,093 - root - [config-split-names] compute JobManager(job_id=65de58fa62c68c8c749fbce3 dataset=ChristophSchuhmann/queries job_info={'job_id': '65de58fa62c68c8c749fbce3', 'type': 'config-split-names', 'params': {'dataset': 'ChristophSchuhmann/queries', 'revision': '641561f9b27193174a37e5a57ffbe258e997ffba', 'config': 'default', 'split': None}, 'priority': <Priority.NORMAL: 'normal'>, 'difficulty': 60}
INFO: 2024-02-27 21:49:47,103 - root - compute 'config-split-names' from config-info for dataset='ChristophSchuhmann/queries' config='default'
INFO: 2024-02-27 21:49:47,105 - root - Cannot compute 'config-split-names' from config-info for self.dataset='ChristophSchuhmann/queries' self.config='default'. Trying to compute it using streaming.
INFO: 2024-02-27 21:49:47,105 - root - compute 'config-split-names' using streaming for dataset='ChristophSchuhmann/queries' config='default'
WARNING: 2024-02-27 21:49:57,009 - root - Heartbeat failed for job 65de58fa62c68c8c749fbce3: JobDocument matching query does not exist.
INFO:     Shutting down
INFO:     Waiting for application shutdown.
INFO:     Application shutdown complete.
INFO:     Finished server process [56]
```