Crash when searching for examples

I get a crash when I do the following:

• Open Qt Creator

Optional steps:

• Go to welcome mode
• Click on examples
• type a couple of letters into the search box

— Note: Searching for examples works as expected

Required Steps:

• Switch to edit mode
• Open Tools>Options>Build & Run>Qt Versions
• Do NOT touch anything on the Qt versions page
• Click OK to close the Settings Window

• Go back to welcome mode
• Select examples
• Type a letter into the search field

---> CRASH.

Apparently the m_qtVersions held by the Model are no longer valid.

In general it is not a good idea to hold on to BaseQtVersion *, but it should be OK here as the versions should get updated whenever the Qt versions change. That update seems to work fine while welcome mode is visible, it fails to happen when it is not.