Exception in NVDA screen reader when hovering over text edit (due to invalid return value)

When the NVDA screen reader is running, hovering with the mouse pointer over a place in a text edit (or the coding area in Qt Creator) where no character is, triggers an exception in the NVDA screen reader because Qt's ITextProvider::RangeFromPoint implementation behaves incorrectly.

Sample steps to reproduce:

1. start the NVDA screen reader (tested with 2023.1 and git master as of commit a85afcef63e536583cff077d2348d6541a3889a5)
2. run the customtypesending example from qtbase (examples\corelib\tools\customtypesending\customtypesending.exe)
3. hover over the text field with the mouse
4. check NVDA log

Result:

This exception can be seen in the NVDA log:

ERROR - eventHandler.executeEvent (19:18:09.994) - MainThread (5180):
error executing event: mouseMove on <NVDAObjects.Dynamic_EditableTextWithAutoSelectDetectionUIA object at 0x08251370> with extra args of {'x': 2785, 'y': 390}
Traceback (most recent call last):
  File "eventHandler.pyc", line 300, in executeEvent
  File "eventHandler.pyc", line 101, in __init__
  File "eventHandler.pyc", line 110, in next
  File "NVDAObjects\__init__.pyc", line 1212, in event_mouseMove
  File "NVDAObjects\UIA\__init__.pyc", line 904, in expand
  File "monkeyPatches\comtypesMonkeyPatches.pyc", line 32, in __call__
ValueError: NULL COM pointer access
 

Further notes:

• This is with the "Enable mouse tracking" option enabled in NVDA (which is the case by default).
• When using an NVDA test version or explicitly enabling the "Play a sound for logged errors" in NVDA, NVDA constantly "beeps" while moving the cursor over the edit, which is how I originally ran into this issue.