Fix an Issue with Removing Trailing Spaces not Working on Empty Lists Items with No List Item Spaces

[pjkaufman]

Fixes #1329

There was an issue where if a list indicator was present with no whitespace or content after it, it would cause an error where the start index was a higher value than the end index. That caused an issue with setting the value.

Changes Made:

• Add a test for the scenario in question
• Update logic for starting index to not get incremented once more if the start is equal to the end