Not plotting due to a shapely.errors.GEOSException

### Describe the bug

Again this is a fairly standard error that I get a lot for various different reasons including memory problems, particularly when plotting ensembles. Sometimes it happens, sometimes it doesn’t (without changing code or memory allowances) and I have never got to the bottom of it. It may also impact one time in the file.

Usually I would just mark this as “succeeded” in a workflow or skip the time that is causing the problem and move on to the next time.

### How to reproduce
Steps to reproduce the behaviour:

Difficult to reproduce.

@jfrost-mo has never seen this.

### Expected behaviour

**QUESTION:** is it worth having a try/except with the plotting to print out a warning message that X time does not plot due to this error, and then continue plotting the other times.

No file or test is named. Start by locating the plotting entry point and reproducing the shapely.errors.GEOSException during ensemble or per-time plotting, if possible. Done means determining the expected behavior for a failing time and verifying that the agreed handling is covered by an appropriate test or documented reproduction.

Written by the indexing model from the issue text.