Allow all errors to be handled by postcss

Doesn't make sense to mix promise rejections with throwing manually

Author: simonsmith

lib/index.js

@@ -64,10 +64,6 @@ var defaults = {
  */
 
 function preprocessor(css, options) {
-  if (typeof css !== 'string') {
-    throw new Error('suitcss-preprocessor: did not receive a String');
-  }
-
   options = mergeOptions(options);
 
   var plugins = options.use.map(function (p) {

test/test.js

@@ -19,9 +19,8 @@ describe('suitcss', function () {
     });
   });
 
-  it('should throw if css is not a string', function() {
-    expect(function() {suitcss(null);}).to.throw(Error);
-    expect(function() {suitcss({});}).to.throw(Error);
+  it('should handle invalid input', function() {
+    expect(function() {suitcss(null);}).to.throw(TypeError);
   });
 
   describe('using options', function() {