fdo#42771: Fix crash when loading an invalid .fodt.
fdo#42771: Fix crash when loading an invalid .fodt.

createTextCursorByRange() likes to throw runtime exception, even though it
just means 'we were unable to create the cursor'.

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core