fix exception with empty text modules

node_modules/architect-build/build.js

@@ -77,7 +77,7 @@ function build(config, opts, callback){
             if (added[pkg.id])
                 return;
             added[pkg.id] = true;
-            if (!pkg.source)
+            if (pkg.source == null)
                 return;
             if (pkg.deps)
                 pkg.deps.forEach(addModule);