Don't crash when passing includePaths with importer

Closes #412

CHANGELOG.md

@@ -1,3 +1,9 @@
+## 1.10.1
+
+### Node JS API
+
+* Don't crash when passing both `includePaths` and `importer`.
+
 ## 1.10.0
 
 * When two `@media` rules' queries can't be merged, leave nested rules in place

lib/src/node.dart

@@ -259,7 +259,7 @@ NodeImporter _parseImporter(RenderOptions options, DateTime start) {
     importers = [options.importer as JSFunction];
   }
 
-  var includePaths = options.includePaths ?? [];
+  var includePaths = new List<String>.from(options.includePaths ?? []);
 
   RenderContext context;
   if (importers.isNotEmpty) {

pubspec.yaml

@@ -1,5 +1,5 @@
 name: sass
-version: 1.10.0
+version: 1.10.1
 description: A Sass implementation in Dart.
 author: Dart Team <misc@dartlang.org>
 homepage: https://github.com/sass/dart-sass

test/node_api/utils.dart

@@ -4,11 +4,13 @@
 
 import 'dart:async';
 import 'dart:convert';
+import 'dart:js_util';
 
 import 'package:js/js.dart';
 import 'package:test/test.dart';
 
 import 'package:sass/src/io.dart';
+import 'package:sass/src/node/function.dart';
 
 import '../hybrid.dart';
 import 'api.dart';
@@ -60,6 +62,17 @@ Future<RenderError> renderError(RenderOptions options) {
 String renderSync(RenderOptions options) =>
     utf8.decode(sass.renderSync(options).css);
 
+/// Like [renderSync], but goes through the untyped JS API.
+///
+/// This lets us test that we properly cast untyped collections without throwing
+/// type errors.
+String renderSyncJS(Map<String, Object> options) {
+  var result = _renderSyncJS.call(sass, jsify(options)) as RenderResult;
+  return utf8.decode(result.css);
+}
+
+final _renderSyncJS = new JSFunction("sass", "args", "return sass.renderSync(args);");
+
 /// Asserts that rendering via [options] produces an error, and returns that
 /// error.
 RenderError renderSyncError(RenderOptions options) {

test/node_api_test.dart

@@ -6,6 +6,7 @@
 @Tags(const ['node'])
 
 import 'dart:convert';
+import 'dart:js';
 
 import 'package:path/path.dart' as p;
 import 'package:test/test.dart';
@@ -420,6 +421,28 @@ a {
         });
       });
     });
+
+    group("when called with a raw JS collection", () {
+      test("for includePaths", () {
+        expect(
+            renderSyncJS({
+                "data": "@import 'test'",
+                "includePaths": [sandbox]
+            }),
+            equalsIgnoringWhitespace('a { b: c; }'));
+      });
+
+      // Regression test for #412
+      test("for includePaths with an importer", () {
+        expect(
+            renderSyncJS({
+                "data": "@import 'test'",
+                "includePaths": [sandbox],
+                "importer": allowInterop((url, prev) => null)
+            }),
+            equalsIgnoringWhitespace('a { b: c; }'));
+      });
+    });
   });
 
   group("render()", () {