Return original markup if katex fails

Author: mjbvz

src/vs/workbench/contrib/markdown/browser/markedKatexSupport.ts

@@ -150,12 +150,20 @@ export namespace MarkedKatexExtension {
 		};
 	}
 
-	function createRenderer(katex: typeof import('katex').default, options: MarkedKatexOptions, newlineAfter: boolean): marked.RendererExtensionFunction {
+	function createRenderer(katex: typeof import('katex').default, options: MarkedKatexOptions, isBlock: boolean): marked.RendererExtensionFunction {
 		return (token: marked.Tokens.Generic) => {
-			return katex.renderToString(token.text, {
-				...options,
-				displayMode: token.displayMode,
-			}) + (newlineAfter ? '\n' : '');
+			let out: string;
+			try {
+				out = katex.renderToString(token.text, {
+					...options,
+					throwOnError: true,
+					displayMode: token.displayMode,
+				});
+			} catch {
+				// On failure, just use the original text including the wrapping $ or $$
+				out = token.raw;
+			}
+			return out + (isBlock ? '\n' : '');
 		};
 	}