NoSuchElementException when trying to export an empty diagram as SVG

[pcdavid]

• I have checked that this bug has not yet been reported by someone else
• I have checked that this bug appears on Chrome
• I have specified the version : 2022.3.9
• I have specified my environment : Linux

Steps to reproduce

1. Create an empty diagram
2. Try to export it as SVG using the context menu in the explorer
3. Nothing happens from the user's point of view, but an exception is logged on the backend:

Caused by: java.util.NoSuchElementException: No value present
	at java.base/java.util.Optional.get(Optional.java:148) ~[na:na]
	at org.eclipse.sirius.components.collaborative.diagrams.export.svg.DiagramExportService.computeViewBox(DiagramExportService.java:116) ~[classes/:na]
	at org.eclipse.sirius.components.collaborative.diagrams.export.svg.DiagramExportService.addSvgRoot(DiagramExportService.java:78) ~[classes/:na]
	at org.eclipse.sirius.components.collaborative.diagrams.export.svg.DiagramExportService.export(DiagramExportService.java:59) ~[classes/:na]
	at org.eclipse.sirius.components.collaborative.diagrams.handlers.ExportDiagramEventHandler.handle(ExportDiagramEventHandler.java:51) ~[classes/:na]

Why would someone want to export an empty diagram? Here in the example scenario it's triggered manually, but it could be part of a programmatic export/publication of all the diagrams in a project for example.

The technical issue is here when the code does this.xBeginPositions.stream().min(Double::compare).get(); on lists like xBeginPositions that might be empty (which is the case on an empty diagram).

[pcdavid]

Note that the "SonarLint for Eclipse" plug-in highlights this potential issue when opening the file (that's how I found it when looking for something else in that file).