Issues after removing last material from model

Please see the attached recording

Steps to reproduce:

• Create/open a 3D project
• Select cubeModel in Navigator
• Remove Default Material from cube by clicking x in Properties -> Model -> Materials
• Materials combobox is empty and cube is no longer visible in 3D view, as expected.
• Add Default Material to cube again by choosing it from Materials combobox
• Remove Material again by clicking x
• -> Material combobox is not empty, but shows Default Material still
• Click "Default Material" text in Materials combobox
• -> Another combobox with Default Material is created.