Moved some asserts to a better place

lib/cpPolyShape.js

@@ -44,11 +44,6 @@ var polyValidate = function(verts)
 /// The vertexes must be convex and have a clockwise winding.
 var PolyShape = cp.PolyShape = function(body, verts, offset)
 {
-	assert(verts.length >= 4, "Polygons require some verts");
-	assert(typeof(verts[0]) === 'number', 'Polygon verticies should be specified in a flattened list');
-	// Fail if the user attempts to pass a concave poly, or a bad winding.
-	assert(polyValidate(verts), "Polygon is concave or has a reversed winding.");
-
 	this.setVerts(verts, offset);
 	this.type = 'poly';
 	Shape.call(this, body);
@@ -69,6 +64,13 @@ SplittingPlane.prototype.compare = function(v)
 
 PolyShape.prototype.setVerts = function(verts, offset)
 {
+	assert(verts.length >= 4, "Polygons require some verts");
+	assert(typeof(verts[0]) === 'number',
+			'Polygon verticies should be specified in a flattened list (eg [x1,y1,x2,y2,x3,y3,...])');
+
+	// Fail if the user attempts to pass a concave poly, or a bad winding.
+	assert(polyValidate(verts), "Polygon is concave or has a reversed winding. Consider using cpConvexHull()");
+
 	var len = verts.length;
 	var numVerts = len >> 1;