Band plot colors issue

Unexpected behaviour when selecting colors for band plot:

```
lines!(x, y , colormap=:viridis, colorrange=(1, 10), color=5)
```
works perfectly well, but
```
band!(x, y1,y2 , colormap=:viridis, colorrange=(1, 10), color=5)
```
throws the following:
```
TypeError: in typeassert, expected ColorTypes.RGBA{Float32}, got a value of type Float32
```