Add early return for zero duration sounds

[iskandarzulkarnaien]

Fix issue where playing a zero duration sound caused play() to never call stop().

[coveralls]

Pull Request Test Coverage Report for Build 3476

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 36.99%

---

Totals
Change from base Build 3468:	0.0%
Covered Lines:	2690
Relevant Lines:	6512

---

💛 - Coveralls

[geshuming]

What was the issue? I don't think this is a very guard clause, what if duration is negative?

[Aulud]

@TheRealRavager I tested the changes and it does indeed fix the Error: play: audio system still playing previous sound bug. However, I have two suggestions:

(1) For checking the duration of the wave, use the strict comparison operator === instead of ==.

(2) The following Source program still triggers the above bug

const sample = sine_sound(1000, -5);        // supply invalid duration
play(sample);

I propose broadening the guard to return early on any non-positive value of the wave duration.

[iskandarzulkarnaien]

Have made the necessary changes. Thanks for the help

[geshuming]

OK lgtm