[Bug]: Python Nexmark Query 12 is broken 'NoneType' object has no attribute 'time'

### What happened?

```
./gradlew --continue -Dorg.gradle.jvmargs=-Xms2g -Dorg.gradle.jvmargs=-Xmx6g -Dorg.gradle.vfs.watch=false -Pdocker-pull-licenses -Pnexmark.runner=:runners:direct-java "-Pnexmark.args=--manageResources=false --monitorJobs=true --bigQueryTable=nexmark --bigQueryDataset=nexmark_PRs --project=apache-beam-testing --resourceNameMode=QUERY_RUNNER_AND_MODE --exportSummaryToBigQuery=true --tempLocation=gs://temp-storage-for-perf-tests/nexmark --influxDatabase=beam_test_metrics --influxHost=http://10.128.0.96:8086/ --baseInfluxMeasurement=nexmark_PRs --exportSummaryToInfluxDB=true --influxRetentionPolicy=forever --suite=SMOKE --enforceEncodability=true --enforceImmutability=true --runner=DirectRunner --query=12 --numEvents=100000 --generateEventFilePathPrefix=gs://temp-storage-for-perf-tests/nexmark/eventFiles/jenkins-beam_PostCommit_Python_Nexmark_Direct_PR-10/query12-" :sdks:java:testing:nexmark:run

./gradlew --continue -Dorg.gradle.jvmargs=-Xms2g -Dorg.gradle.jvmargs=-Xmx6g -Dorg.gradle.vfs.watch=false -Pdocker-pull-licenses "-Pnexmark.args= --monitor_jobs --big_query_table=nexmark --big_query_dataset=nexmark_PRs --project=apache-beam-testing --resource_name_mode=QUERY_RUNNER_AND_MODE --export_summary_to_big_query --temp_location=gs://temp-storage-for-perf-tests/nexmark --influx_database=beam_test_metrics --influx_host=http://10.128.0.96:8086/ --base_influx_measurement=nexmark_PRs --export_summary_to_influx_db --influx_retention_policy=forever --suite=SMOKE --enforce_encodability --enforce_immutability --runner=DirectRunner --query=12 --num_events=100000 --input=gs://temp-storage-for-perf-tests/nexmark/eventFiles/jenkins-beam_PostCommit_Python_Nexmark_Direct_PR-10/query12-\*" :sdks:python:apache_beam:testing:benchmarks:nexmark:run
```

16:20:22 (MainThread) Created Worker handler for environment ref_Environment_default_environment_1 (beam:env:embedded_python:v1, b'')
16:20:22 (MainThread) Finished listing 1 files in 0.041292428970336914 seconds.
16:20:22 Traceback (most recent call last):
16:20:33 File "/usr/lib/python3.8/runpy.py", line 194, in _run_module_as_main
16:20:33 return _run_code(code, main_globals, None,
16:20:33 File "/usr/lib/python3.8/runpy.py", line 87, in _run_code
16:20:33 exec(code, run_globals)
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/testing/benchmarks/nexmark/nexmark_launcher.py", line 528, in
16:20:33 launcher.run()
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/testing/benchmarks/nexmark/nexmark_launcher.py", line 513, in run
16:20:33 self.run_query(
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/testing/benchmarks/nexmark/nexmark_launcher.py", line 306, in run_query
16:20:33 result = self.pipeline.run()
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/pipeline.py", line 577, in run
16:20:33 return self.runner.run_pipeline(self, self._options)
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/runners/direct/direct_runner.py", line 131, in run_pipeline
16:20:33 return runner.run_pipeline(pipeline, options)
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/runners/portability/fn_api_runner/fn_runner.py", line 201, in run_pipeline
16:20:33 self._latest_run_result = self.run_via_runner_api(
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/runners/portability/fn_api_runner/fn_runner.py", line 222, in run_via_runner_api
16:20:33 return self.run_stages(stage_context, stages)
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/runners/portability/fn_api_runner/fn_runner.py", line 453, in run_stages
16:20:33 bundle_results = self._execute_bundle(
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/runners/portability/fn_api_runner/fn_runner.py", line 781, in _execute_bundle
16:20:33 self._run_bundle(
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/runners/portability/fn_api_runner/fn_runner.py", line 1010, in _run_bundle
16:20:33 result, splits = bundle_manager.process_bundle(
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/runners/portability/fn_api_runner/fn_runner.py", line 1337, in process_bundle
16:20:33 self._send_input_to_****(process_bundle_id, transform_id, elements)
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/runners/portability/fn_api_runner/fn_runner.py", line 1211, in _send_input_to_****
16:20:33 for byte_stream in (byte_streams or []):
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/runners/portability/fn_api_runner/execution.py", line 308, in __iter__
16:20:33 return itertools.chain(*self.partition(1))
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/runners/portability/fn_api_runner/execution.py", line 294, in partition
16:20:33 for wkvs in windowed_key_values(key, windowed_values):
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/transforms/trigger.py", line 1232, in process_entire_key
16:20:33 for wvalue in self.process_elements(state,
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/transforms/trigger.py", line 1442, in process_elements
16:20:33 self.trigger_fn.on_element(value, window, context)
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/transforms/trigger.py", line 722, in on_element
16:20:33 self.underlying.on_element(element, window, context)
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/transforms/trigger.py", line 393, in on_element
16:20:33 '', TimeDomain.REAL_TIME, context.get_current_time() + self.delay)
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/transforms/trigger.py", line 998, in get_current_time
16:20:33 return self._outer.get_current_time()
16:20:33 File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python_Nexmark_Direct_PR/src/sdks/python/apache_beam/transforms/trigger.py", line 973, in get_current_time
16:20:33 return self._clock.time()
16:20:33 AttributeError: 'NoneType' object has no attribute 'time'
16:20:33

### Issue Priority

Priority: 3 (minor)

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