From f7d19a5746e9f9c092fa2aee492f5d4f5ea62f0e Mon Sep 17 00:00:00 2001
From: Michael Telatynski <7t3chguy@gmail.com>
Date: Mon, 10 Jan 2022 11:34:56 +0000
Subject: [PATCH] null-guard dataset mxTheme to prevent html exports from
 exploding (#7493)

---
 src/utils/exportUtils/exportCSS.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/utils/exportUtils/exportCSS.ts b/src/utils/exportUtils/exportCSS.ts
index 9f52edf89a..ceafed174b 100644
--- a/src/utils/exportUtils/exportCSS.ts
+++ b/src/utils/exportUtils/exportCSS.ts
@@ -40,7 +40,7 @@ const getExportCSS = async (usedClasses: Set<string>): Promise<string> => {
     // only include bundle.css and the data-mx-theme=light styling
     const stylesheets = Array.from(document.styleSheets).filter(s => {
         return s.href?.endsWith("bundle.css") ||
-            (s.ownerNode as HTMLStyleElement).dataset.mxTheme.toLowerCase() === "light";
+            (s.ownerNode as HTMLStyleElement).dataset.mxTheme?.toLowerCase() === "light";
     });
 
     let css = "";