Throw error on ScrollComponent.wrap() with nonexisting layer

framer/Components/ScrollComponent.coffee

@@ -391,6 +391,9 @@ class exports.ScrollComponent extends Layer

wrapComponent = (instance, layer, options = {correct:true}) ->

	if not (layer instanceof Layer)
		throw new Error("ScrollComponent.wrap expects a layer, not #{layer}. Are you sure the layer exists?")

	# This function wraps the given layer into a scroll or page component. This is
	# great for importing from Sketch or Photoshop.

test/tests/ScrollComponentTest.coffee

@@ -77,3 +77,7 @@ describe "ScrollComponent", ->
			
			delete layerA._properties.backgroundColor
			scroll = ScrollComponent.wrap(layerA)

		it "should throw a warning on no layer", ->
			f = -> ScrollComponent.wrap()
			f.should.throw()