Alpha value of 0 breaks rgb

[nickofthyme]

When using an alpha value with d3.rgb, via rgba or hsla colors strings, the color values return NaN.

Is this expected behavior?

tested on d3-color@1.4.0

d3.rgb('hsla(240,100%,25%,0)');

// returns
{
  r: NaN,
  b: NaN,
  g: NaN,
  opacity: 0,
}

d3.rgb('rgba(0,0,0,0)');

// returns
{
  r: NaN,
  b: NaN,
  g: NaN,
  opacity: 0,
}

Also interesting to note that the behavior of non-zero, but close to zero, alpha values return the expected color.

d3.rgb('rgba(0,0,0,0.001)');

// returns
{
  r: 0,
  b: 0,
  g: 0,
  opacity: 0.001,
}

[nickofthyme]

duplicate of #52