Merge pull request #6 from softprops/stdout-w-err

combine stderr with stdout on err

src/exec.rs

@@ -35,6 +35,6 @@ pub async fn exec(
     if output.status.success() {
         Ok(from_utf8(&output.stdout)?.to_string())
     } else {
-        Err(anyhow!(from_utf8(&output.stderr)?.to_string()).into())
+        Err(anyhow!(vec![from_utf8(&output.stderr)?, from_utf8(&output.stdout)?].join("\n")).into())
     }
 }