Plotting fails silently when handed bad data, or produces confusing error messages

[phx-mkoninckx]

For example: http://codepen.io/anon/pen/ZObgwz
No error messages are produced, even at the console, when running this code (attempting to plot scatter3d with no z-axis data). It would be more developer-friendly if an error message was produced that indicated why no data was plotted.

[etpinard]

I wouldn't call this failing really.

scatter3d needs z array in order to be considered visible.

We could make it clearer in our docs (maybe by adding required meta tag in our attribute declarations) and/or expose some other way to inform users about attribute coercion.

In any case, this is a duplicate of #598