Don't try to cast an error to JsError

Dart's runtime understanding of what a "JsError" is isn't sufficient
to make sense of everything that might be thrown by, for example, a
custom function with an error.

CHANGELOG.md

@@ -1,3 +1,10 @@
+## 1.32.5
+
+### JS API
+
+* Avoid possible mangled error messages when custom functions or importers throw
+  unexpected exceptions.
+
 ## 1.32.4
 
 * No user-visible changes.

lib/src/node.dart

@@ -65,13 +65,13 @@ void main() {
 ///
 /// [render]: https://github.com/sass/node-sass#options
 void _render(
-    RenderOptions options, void callback(JsError error, RenderResult result)) {
+    RenderOptions options, void callback(Object error, RenderResult result)) {
   if (options.fiber != null) {
     options.fiber.call(allowInterop(() {
       try {
         callback(null, _renderSync(options));
       } catch (error) {
-        callback(error as JsError, null);
+        callback(error, null);
       }
       return null;
     })).run();

pubspec.yaml

@@ -1,5 +1,5 @@
 name: sass
-version: 1.32.4
+version: 1.32.5
 description: A Sass implementation in Dart.
 author: Sass Team
 homepage: https://github.com/sass/dart-sass