NullReferenceException when displaying tooltip for the suggestion mode item

[AmadeusW]

Version Used: 15.6.5

Steps to Reproduce:

1. Ctrl+Alt+Space to activate suggestion mode
2. Type in the editor
3. Use the arrow up to navigate to the suggestion item

Expected Behavior:

Displaying the tooltip does not cause an error

Actual Behavior:

There is an error when creating tooltip for the suggestion item

System.NullReferenceException: Object reference not set to an instance of an object.
at 
Microsoft.CodeAnalysis.Editor.Implementation.IntelliSense.Completion.Presentation.ToolTipProvider.CancellableContentControl..ctor(ToolTipProvider toolTipProvider, CustomCommitCompletion item)
at 
Microsoft.CodeAnalysis.Editor.Implementation.IntelliSense.Completion.Presentation.ToolTipProvider.GetUIElement(Completion itemToRender, ICompletionSession context, UIElementType elementType)
at 
Microsoft.VisualStudio.Language.Intellisense.Implementation.Helpers.<>c__DisplayClass7_0`2.<FindUIElement>b__0(IUIElementProvider`2 provider)
at 
Microsoft.VisualStudio.Text.Utilities.GuardedOperations.InstantiateExtension[TExtension,TMetadata,TExtensionInstance](Object errorSource, Lazy`2 provider, Func`2 getter)
--- End of stack trace from previous location where exception was thrown ---
at 
Microsoft.VisualStudio.Telemetry.WindowsErrorReporting.WatsonReport.GetClrWatsonExceptionInfo(Exception exceptionObject)

Note that this will be fixed through the new completion API in #25770 via @dpoeschl

[ivanbasov]

Could not reproduce with the current version of VS (2019 Preview 2). It seems to be fixed maybe with #32307