Application crashes when the workbench is forced to open a deleted representation

[gcoutable]

Steps to reproduce

1. Create Flow project and two Topography diagrams
2. Open the two topography diagrams
3. From the explorer delete one of the two topography
4. A message telling that the representation does not exist should be visible
5. Without closing the removed representation, switch to the other topography diagram
6. Close the existing representation (small x on the tab)

Expected result

The application should not crash, and maybe it should select the tab of the representation that does not exist and display the informative message accordingly

Actual result

The application crashes because the workbench is forces to open a representation that does not exist.

application-crash.mp4