Fix error when dynamic importing js files which imports raw files (#190)

src/builtins/bundle-loader.js

@@ -32,7 +32,10 @@ function loadBundle(bundle) {
   }
 
   var type = bundle.match(/\.(.+)$/)[1].toLowerCase();
-  return bundles[bundle] = bundleLoaders[type](getBundleURL() + bundle);
+  var bundleLoader = bundleLoaders[type];
+  if (bundleLoader) {
+    return bundles[bundle] = bundleLoader(getBundleURL() + bundle);
+  }
 }
 
 function loadJSBundle(bundle) {

test/integration/dynamic-references-raw/index.js

@@ -0,0 +1,7 @@
+var local = import('./local');
+
+module.exports = function () {
+  return local.then(function (l) {
+    return l.a + l.b;
+  });
+};

test/integration/dynamic-references-raw/local.js

@@ -0,0 +1,4 @@
+import raw from './test.txt';
+
+exports.a = 1;
+exports.b = 2;

test/integration/dynamic-references-raw/test.txt

@@ -0,0 +1 @@
+raw file

test/javascript.js

@@ -58,6 +58,27 @@ describe('javascript', function() {
     assert.equal(await output(), 3);
   });
 
+  it('should dynamic import files which import raw files', async function() {
+    let b = await bundle(
+      __dirname + '/integration/dynamic-references-raw/index.js'
+    );
+
+    assertBundleTree(b, {
+      name: 'index.js',
+      assets: ['index.js', 'bundle-loader.js', 'bundle-url.js'],
+      childBundles: [
+        {
+          assets: ['local.js', 'test.txt'],
+          childBundles: ['test.txt']
+        }
+      ]
+    });
+
+    let output = run(b);
+    assert.equal(typeof output, 'function');
+    assert.equal(await output(), 3);
+  });
+
   it('should return all exports as an object when using ES modules', async function() {
     let b = await bundle(__dirname + '/integration/dynamic-esm/index.js');