Ignore null source maps

fixes #84
closes #90

lib/loader.js

@@ -14,7 +14,7 @@ module.exports = function(content, map) {
 	var root = query.root;
 	var moduleMode = query.modules || query.module;
 
-	if(typeof map !== "string") {
+	if(map !== null && typeof map !== "string") {
 		map = JSON.stringify(map);
 	}
 

test/helpers.js

@@ -52,6 +52,26 @@ exports.test = function test(name, input, result, query, modules) {
 	});
 };
 
+exports.testWithMap = function test(name, input, map, result, query, modules) {
+	it(name, function() {
+		var output = cssLoader.call({
+			options: {
+				context: ""
+			},
+			loaders: [{request: "loader"}],
+			loaderIndex: 0,
+			context: "",
+			resource: "test.css",
+			request: "css-loader!test.css",
+			query: query,
+			emitError: function(message) {
+				throw new Error(message);
+			}
+		}, input, map);
+		assetEvaluated(output, result, modules);
+	});
+};
+
 exports.testLocals = function testLocals(name, input, result, query, modules) {
 	it(name, function() {
 		var output = cssLoaderLocals.call({

test/sourceMapTest.js

@@ -0,0 +1,12 @@
+/*globals describe */
+
+var testWithMap = require("./helpers").testWithMap;
+
+describe("falsy source maps", function() {
+	testWithMap("null map doesn't cause an error", ".class { a: b c d; }", null, [
+		[1, ".class { a: b c d; }", ""]
+	]);
+	testWithMap("undefined map doesn't cause an error", ".class { a: b c d; }", undefined, [
+		[1, ".class { a: b c d; }", ""]
+	]);
+});