amberc.js: writing of .js files is now async

bin/amberc.js

@@ -400,10 +400,14 @@ function node_compile(filesArray) {
 		} else {
 			console.log("Exporting " + (defaults.deploy ? "(debug + deploy)" : "(debug)") + " category "
 				+ val + " as " + val + defaults.suffix_used + ".js" + (defaults.deploy ? " and " + val + defaults.suffix_used + ".deploy.js" : ""));
-			fs.writeFileSync(val + defaults.suffix_used + ".js", smalltalk.Exporter._new()._exportPackage_(val));
-			if (defaults.deploy) {
-				fs.writeFileSync(val + defaults.suffix_used + ".deploy.js", smalltalk.StrippedExporter._new()._exportPackage_(val));
-			}
+			fs.writeFile(val + defaults.suffix_used + ".js", smalltalk.Exporter._new()._exportPackage_(val), function(err){
+				if (err) throw err;
+				if (defaults.deploy) {
+					fs.writeFile(val + defaults.suffix_used + ".deploy.js", smalltalk.StrippedExporter._new()._exportPackage_(val), function(err){
+						if (err) throw err;
+					});
+				};
+			});
 		}
 	});
 }