Simplify steal-tools bundle with pump library

lib/build/bundle.js

@@ -1,4 +1,5 @@
-var assign = require("lodash").assign;
+var pump = require("pump");
+var assign = require("lodash/assign");
 var minify = require("../stream/minify");
 var transpile = require("../stream/transpile");
 var concat = require("../bundle/concat_stream");
@@ -34,32 +35,23 @@ module.exports = function(config, options) {
 		}
 	});
 
-	var graphStream = createBundleGraphStream(config, options);
-	var filteredGraphStream = graphStream.pipe(filterBundleGraph());
-	var transpileStream = filteredGraphStream.pipe(transpile());
-	var minifyStream = transpileStream.pipe(minify());
-	var buildStream = minifyStream.pipe(makeBundle());
-	var concatStream = buildStream.pipe(concat());
-
 	return new Promise(function(resolve, reject) {
-		var writeStream = buildStream.pipe(createWriteStream());
+		var writeStream = pump(
+			createBundleGraphStream(config, options),
+			filterBundleGraph(),
+			transpile(),
+			minify(),
+			makeBundle(),
+			concat(),
+			createWriteStream(),
+			function(err) {
+				if (err) reject(err);
+			}
+		);
 
 		writeStream.on("data", function(data){
 			this.end();
 			resolve(data);
 		});
-
-		var streams = [
-			graphStream,
-			filteredGraphStream,
-			transpileStream,
-			minifyStream,
-			buildStream,
-			concatStream
-		];
-
-		streams.forEach(function(stream) {
-			stream.on("error", reject);
-		});
 	});
 };