The Editor will crash if an image uses sliced sprites with no empty space in the centre.

Reproduction Steps:
1. Open the scene 'Scene'
2. Select Canvas > Image Bar
3. Set the Image Type to Tiled
4. The Editor will lock up. In Task Manager you'll see Unity expanding to use all the system memory available (has even crashed my OS in during testing)

Note that this issue doesn't happen if you select the asset Bar.png and use the Sprite Editor to change the borders to have a space in the centre (31 either side instead of 32, for example).