From 016436ae1882e2104fc085aa098b5925ef547305 Mon Sep 17 00:00:00 2001
From: William Wall <wwall@caci.com>
Date: Wed, 19 Sep 2018 15:04:14 -0600
Subject: [PATCH] Check that tile is ImageTile before using it

---
 src/ol/renderer/webgl/TileLayer.js | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/ol/renderer/webgl/TileLayer.js b/src/ol/renderer/webgl/TileLayer.js
index fc07e504a0..9c72597c9f 100644
--- a/src/ol/renderer/webgl/TileLayer.js
+++ b/src/ol/renderer/webgl/TileLayer.js
@@ -5,6 +5,7 @@
 // FIXME animated shaders! check in redraw
 
 import LayerType from '../../LayerType.js';
+import ImageTile from '../../ImageTile.js';
 import TileRange from '../../TileRange.js';
 import TileState from '../../TileState.js';
 import TileSource from '../../source/Tile.js';
@@ -286,6 +287,11 @@ class WebGLTileLayerRenderer extends WebGLLayerRenderer {
         const tilesToDraw = tilesToDrawByZ[zs[i]];
         for (const tileKey in tilesToDraw) {
           tile = tilesToDraw[tileKey];
+
+          if (!(tile instanceof ImageTile)) {
+            continue;
+          }
+
           tileExtent = tileGrid.getTileCoordExtent(tile.tileCoord, tmpExtent);
           u_tileOffset[0] = 2 * (tileExtent[2] - tileExtent[0]) /
               framebufferExtentDimension;