Bug: `allParToVisibleParIndex` throws Exception when allParIndex is >= size of visible paragraphs but <= area's last paragraph index

[JordanMartinez]

As originally reported here...

Expected Behavior

allParToVisibleParIndex(int allParIndex) should return Optional.of(correspondingVisibleParIndex) for all valid allParIndex arguments.

Actual Behavior

allParToVisibleParIndex(int allParIndex) throws an exception if allParIndex is within the bounds of the area's paragraph indices but less than the last visible paragraph index.

This can easily be fixed by checking the argument against the size of the area's total paragraphs rather than the visible ones.