RemoveDuplicatesFromSortedArray is not working as expected and output shows extra element in an array

[ghost]

LeetCode-Swift/Array/RemoveDuplicatesFromSortedArray.swift
The solution to the above problem doesn't seems to be correct.

e.g
Input: [1,1,2,2,5,5,6,8,9,9,9]
Program output in Leetcode console: [1,2,5,6,8,9]
Program Output in Xcode Playground : [1, 2, 5, 6, 8, 9, 6, 8, 9, 9, 9]
Expected Output is: [1,2,5,6,8,9]