ElementAtOrDefault bugs

ElementAtOrDefault is defined as:

/**
 * Returns the element at a specified index in a sequence or a default value if the index is out of range.
 */
public ElementAtOrDefault(index: number): T {
  return this.ElementAt(index) || undefined
}

However the description doesn’t match the implementation (tho the test does), and the implementation is buggy anyway - c.f. FirstOrDefault().

Specifically, indexing off the end (or start, which is not checked for by the way - another bug) should return undefined, rather than throwing, to match the description and .Net behaviour.

Also, if I have a list of numbers that happen to be 0, and I ask for an index in range, I get undefined not 0.

[chris-findlay]

• Fixing ElementAt to also throw for -1 etc;
• Fixing ElementAtOrDefault to check for out of bounds (either side) explicitly and return undefined in those cases;
• Fixing ElementAtOrDefault to check for in bounds (i.e. the else to the above if) and only return the value at that index, with no fallback clause.

[kutyel]

Sorry for the delay @chris-findlay, it was pretty straight-forward to fix! 😉