From 1ca841e6c03573c00f5143b254010f5707d47c1e Mon Sep 17 00:00:00 2001
From: Jarek Radosz <jradosz@gmail.com>
Date: Sun, 17 Feb 2019 14:32:16 +0100
Subject: [PATCH] Add a fallback for missing uiContextualLayerPositioner (#781)

---
 source/browser.ts | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/source/browser.ts b/source/browser.ts
index 58aa83dbb..0f3e4583b 100644
--- a/source/browser.ts
+++ b/source/browser.ts
@@ -21,17 +21,20 @@ async function withMenu(
 	menuButtonElement.click();
 
 	// Wait for the menu to close before removing the 'hide-dropdowns' class
-	const menuLayer = document.querySelector<HTMLElement>(
-		'.uiContextualLayerPositioner:not(.hidden_elem)'
-	)!;
+	const menuLayer = document.querySelector('.uiContextualLayerPositioner:not(.hidden_elem)');
 
-	const observer = new MutationObserver(() => {
-		if (menuLayer.classList.contains('hidden_elem')) {
-			classList.remove('hide-dropdowns');
-			observer.disconnect();
-		}
-	});
-	observer.observe(menuLayer, {attributes: true, attributeFilter: ['class']});
+	if (menuLayer) {
+		const observer = new MutationObserver(() => {
+			if (menuLayer.classList.contains('hidden_elem')) {
+				classList.remove('hide-dropdowns');
+				observer.disconnect();
+			}
+		});
+		observer.observe(menuLayer, {attributes: true, attributeFilter: ['class']});
+	} else {
+		// Fallback in case .uiContextualLayerPositioner is missing
+		classList.remove('hide-dropdowns');
+	}
 
 	await callback();
 }