When editing in-document subcomponent, adding modules doesn't work and removing them crashes

While editing in-document subcomponent, trying to add a new module does nothing. Removing and existing module will crash.

To repro:

• Create new project
• Add Component item
• Make sure component has a child item
• Add QtQuick3D module
• Select component and press F2 to change into in-document subcomponent edit mode
• Add any module, e.g. QtQuick.Studio.Effects -> Module is not added
• Remove QtQuick3D module -> Creator crashes

Likely all module interaction should be disabled when editing in-document subcomponents.