Spark's pipeline result throws exceptions

Spark's pipeline result seems to allow throwing Exceptions from `waitUntilFinish()` methods.

[https://github.com/apache/beam/blob/master/runners/spark/src/main/java/org/apache/beam/runners/spark/SparkPipelineResult.java#L101](https://github.com/apache/beam/blob/master/runners/spark/src/main/java/org/apache/beam/runners/spark/SparkPipelineResult.java#L101)

Documentation on PipelineResult does not mention this possibility. As a result, when I am running pipelines from Scio, it does swallow such exceptions because if does not expect them

[https://github.com/spotify/scio/issues/1617](https://github.com/spotify/scio/issues/1617)

Should the Spark Runner just log those exceptions and update it's state of is documentation about `PipelineResult.waitUntilFinish()` not up to date?

Imported from Jira [BEAM-6484](https://issues.apache.org/jira/browse/BEAM-6484). Original Jira may contain additional context.
Reported by: JozoVilcek.