Include stderr in simplespawner output

package.json

@@ -1,6 +1,6 @@
 {
   "name": "async-spawner",
-  "version": "0.1.6",
+  "version": "0.1.7",
   "description": "Simple process spawning utility for node.js",
   "main": "./lib/index.js",
   "types": "./@types/index.d.ts",

src/index.ts

@@ -4,13 +4,13 @@ import Emittery from "emittery";
 export default function simpleSpawn(
   cmd: string,
   arg: string[]
-): Promise<string> {
+): Promise<{ stdout: string; stderr: string }> {
   const process = spawn(cmd, arg);
   let output = "";
   let err = "";
   return new Promise((resolve, reject) => {
     process.on("close", (code) => {
-      code === 0 ? resolve(output) : reject(err);
+      code === 0 ? resolve({ stdout: output, stderr: err }) : reject(err);
     });
     process.stdout.on("data", (data) => (output += data.toString("utf-8")));
     process.stderr.on("data", (data) => (err += data.toString("utf-8")));