Fix a couple of issues

[cassioscabral]

This PR is suppose to fix the issue #49 and #25

For #25 there is no right solution at the moment. Tinycolor will set the values to black if hsl's "L"(for light, same for V in hsv) reach zero. The solution would be use some kind of cache or avoid to reach zero when moving the circle, that's what I did.

#49 was solved by checking if data exists before using.

@xiaokaike could you download this branch and test it out before accepting it ? I created the dist on Windows and I can't trust it, but should it be fine.

[okydk]

I've tested and can confirm #49 is fixed. As of #25 we might await fix in TinyColor?

[cassioscabral]

I thought about it, but unfortunately this is a known issue since 2015 =/ (bgrins/TinyColor#86)

What I found in that issue is that Tinycolor convert hsv or hsl or any other to RGB. So if you reach the black or white, both extreme colors, it will convert to RGB(0, 0, 0) or RGB(255, 255, 255) losing information in the process. My solution was to avoid the saturation reach zero(when zero it's reached change to 0.01 instead) to avoid triggering the change, would still be possible to change manually though. With that, visually the user will not notice the jump.

I checked someone else's project(tangrams/tangram-play#576) that had the same problem and they used a cache approach, they are using React and probably some state management lib(redux or any other similar) which make this approach even better. But we don't have that here.

[okydk]

Arh I see. I've tested the 'Chrome' color-picker and there still seems to be an issue when selecting colors on the far left, as well as turning alpha to 0 which turns the active color into rgb.