MeshDraft.FlatRevolutionSurface throws ArgumentOutOfRangeException with generateUV = false

[BasmanovDaniil]

Both lowerRingUV and upperRingUV are empty:

ProceduralToolkit/Scripts/MeshDraftPrimitives.cs

Lines 510 to 530 in 70e7503

	var draft = new MeshDraft {name = "Flat revolution surface"};
	for (int y = 0; y < ringsVertices.Count - 1; y++)
	{
	var lowerRingVertices = ringsVertices[y];
	var upperRingVertices = ringsVertices[y + 1];
	var lowerRingUV = ringsUV[y];
	var upperRingUV = ringsUV[y + 1];
	for (int x = 0; x < horizontalSegments; x++)
	{
	Vector3 v00 = lowerRingVertices[x + 1];
	Vector3 v01 = upperRingVertices[x + 1];
	Vector3 v11 = upperRingVertices[x];
	Vector3 v10 = lowerRingVertices[x];
	Vector2 uv00 = lowerRingUV[x + 1];
	Vector2 uv01 = upperRingUV[x + 1];
	Vector2 uv11 = upperRingUV[x];
	Vector2 uv10 = lowerRingUV[x];
	draft.AddQuad(v00, v01, v11, v10, true, uv00, uv01, uv11, uv10);
	}
	}
	return draft;