fix(package-analyzer): find location of packages outside of node_modules

fixes aurelia#567

lib/build/package-analyzer.js

@@ -28,7 +28,7 @@ exports.PackageAnalyzer = class {
     description.source = 'custom';
     description.loaderConfig = loaderConfig;
 
-    return Promise.resolve(description);
+    return loadPackageMetadata(this.project, description).then(() => description);
   }
 };
 
@@ -37,6 +37,11 @@ function loadPackageMetadata(project, description) {
     .then(() => fs.readFile(description.metadataLocation))
     .then(data => {
       description.metadata = JSON.parse(data.toString());
+    })
+    .catch(e => {
+      console.log(`Unable to load package metadata (package.json) of ${description.name}:`);
+      console.log(e);
+      throw e;
     });
 }
 
@@ -73,8 +78,19 @@ function setLocation(project, description) {
         description.location = packageFolder;
         description.metadataLocation = path.join(description.location, 'package.json');
       });
+  case 'custom':
+    if (!description.loaderConfig || !description.loaderConfig.packageRoot) {
+      return Promise.reject(`Error: packageRoot property not defined for the "${description.name}" package. It is recommended to` +
+      'define the packageRoot for packages outside the node_modules folder, so that the files end up in' +
+      'the correct bundle');
+    }
+
+    description.location = path.resolve(project.paths.root, description.loaderConfig.packageRoot);
+    description.metadataLocation = path.join(description.location, 'package.json');
+
+    return Promise.resolve();
   default:
-    throw new Error(`The package source "${description.source}" is not supported.`);
+    return Promise.reject(`The package source "${description.source}" is not supported.`);
   }
 }