catch CSS syntax errors before rework-css parses

index.js

@@ -42,11 +42,27 @@ module.exports = function loader(content, sourceMap) {
   }
 
   // process
-  return rework(content)
-    .use(reworkPlugin)
-    .toString({
-      sourcemap: this.sourceMap || options.sourceMap
-    });
+  //  rework will throw on css syntax errors
+  var FILENAME_PLACEHOLDER = '<filename>';
+  try {
+    return rework(content, { source: FILENAME_PLACEHOLDER })
+      .use(reworkPlugin)
+      .toString({
+        sourcemap: this.sourceMap || options.sourceMap
+      });
+  }
+  //  fail gracefully
+  catch(exception) {
+    var message = ('CSS syntax error (resolve-url-loader did not operate)' + exception.message)
+        .replace(FILENAME_PLACEHOLDER, '');
+    if (options.fail) {
+      this.emitError(message);
+    }
+    else if (!options.silent) {
+      this.emitWarning(message);
+    }
+    return content; // original content unchanged
+  }
 
   /**
    * Convert each relative file in the given array to absolute path.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "resolve-url-loader",
-  "version": "1.0.3",
+  "version": "1.1.0",
   "description": "Webpack loader that resolves relative paths in url() statements based on the original source file",
   "main": "index.js",
   "scripts": {

readme.md

@@ -40,6 +40,9 @@ require('!style!css!resolve-url!sass?sourceMap!./file.scss');
 
 Note that **source maps** must be enabled on any preceding loader. In the above example we use `sass?sourceMap`.
 
+In some use cases (no preceding transpiler) there will be no incoming source map. Therefore we do not warn if the
+source-map is missing.
+
 ### Apply via webpack config
 
 It is preferable to adjust your `webpack.config` so to avoid having to prefix every `require()` statement:
@@ -68,6 +71,10 @@ if you know what you are doing.
 
 * `sourceMap` Generate a source-map.
 
+* `silent` Do not display warnings on CSS syntax error.
+
+* `fail` Syntax errors will result in an error.
+
 ## How it works
 
 The incoming source-map is used to resolve the original file. This is necessary where there was some preceding transpile