From 164635f28cd9196d20dbb082257230012bf55fa1 Mon Sep 17 00:00:00 2001
From: ahocevar <andreas.hocevar@gmail.com>
Date: Fri, 25 Jan 2019 11:59:19 +0100
Subject: [PATCH] Safer check for window.screen

---
 src/ol/source/Tile.js | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/ol/source/Tile.js b/src/ol/source/Tile.js
index 9a60057986..3eda3a99c0 100644
--- a/src/ol/source/Tile.js
+++ b/src/ol/source/Tile.js
@@ -75,8 +75,9 @@ class TileSource extends Source {
       if (tileGrid) {
         toSize(tileGrid.getTileSize(tileGrid.getMinZoom()), tileSize);
       }
-      const width = screen ? (screen.availWidth || screen.width) : 1920;
-      const height = screen ? (screen.availHeight || screen.height) : 1080;
+      const canUseScreen = 'screen ' in self;
+      const width = canUseScreen ? (screen.availWidth || screen.width) : 1920;
+      const height = canUseScreen ? (screen.availHeight || screen.height) : 1080;
       cacheSize = 2 * Math.ceil(width / tileSize[0]) * Math.ceil(height / tileSize[1]);
     }