Warn instead of fail on exceptions thrown from postcss (#1580)

* postcss was introduced in #1458 for use within adaptCssForReplay
* #1600 fixes the main case where invalid css could be introduced when if valid css from the output of `sheet.cssRules` was split according to how it was split across text nodes of the <style>
* the guard introduced here is still useful as we likely in future will switch to capturing the raw stylesheet contents (both <style> and <link>), at which point we will be much less confident of getting valid css

packages/rrweb-snapshot/src/rebuild.ts

@@ -62,11 +62,17 @@ export function adaptCssForReplay(cssText: string, cache: BuildCache): string {
   const cachedStyle = cache?.stylesWithHoverClass.get(cssText);
   if (cachedStyle) return cachedStyle;
 
-  const ast: { css: string } = postcss([
-    mediaSelectorPlugin,
-    pseudoClassPlugin,
-  ]).process(cssText);
-  const result = ast.css;
+  let result = cssText;
+  try {
+    const ast: { css: string } = postcss([
+      mediaSelectorPlugin,
+      pseudoClassPlugin,
+    ]).process(cssText);
+    result = ast.css;
+  } catch (error) {
+    console.warn('Failed to adapt css for replay', error);
+  }
+
   cache?.stylesWithHoverClass.set(cssText, result);
   return result;
 }