Instantiating new buffer in Safari throws an error

[dy]

regl.buffer({
	data: null,
	usage: 'dynamic',
	type: 'float'
},

throws an error in safari, related plotly/plotly.js#2593, plotly/plotly.js#2543, plotly/plotly.js#2457.

That is trivial to fix by making sure default data is not null.