Cosmetic Index out of bound check fix.

[martinfrances107]

I porting this test to rust... I found an accidental inconsistency that because of javascript being a bit screwy
well it accidentally does the right thing...

I still consider it bug as someone modifying/maintaining the java script may not see the bug until too late..

this test

tape("delaunay.voronoi() for one point returns the bounding rectangle", test => {
  let voronoi = Delaunay.from([[0, 0]]).voronoi([-1, -1, 2, 2]);
  test.equal(voronoi.renderCell(0), "M2,-1L2,2L-1,2L-1,-1Z");
  test.equal(voronoi.render(), null);
});

When I watch the code below run in a debugger.
(delaunay.js)

    // degenerate case: 1 or 2 (distinct) points
    if (hull.length <= 2 && hull.length > 0) {
      this.triangles = new Int32Array(3).fill(-1);
      this.halfedges = new Int32Array(3).fill(-1);
      this.triangles[0] = hull[0];
      this.triangles[1] = hull[1];   /* index out of bounds */
      this.triangles[2] = hull[1];   /* index out of bounds */
      inedges[hull[0]] = 1;
      if (hull.length === 2) inedges[hull[1]] = 0; /* move statements here */
    }

hull has a length of 1 with the contents of [0];

initially this.triangles is set to [-1, -1, -1]

hull[1] is formally undefined
and because Javascript is screwy

this.triangles[1] = undefined is a noop ... well after this.triangles[1] is still -1

My proposal is to move the statements labelled "index out of bounds" down into the
existing if statements which covers this case...

it will have no effect.. just make the intent of the code clear.
(actually it does less work, but that is not the advantage I am talking about)

I am about to generate a PR.

[Fil]

fixed by 54795cb