fix(std/node): fix readFile types, add encoding types (#6451)

1 files changed, 17 insertions, 5 deletions

diff --git a/std/node/_fs/promises/_fs_readFile.ts b/std/node/_fs/promises/_fs_readFile.ts
index 9e4a4ed43..83ef9ac50 100644
--- a/std/node/_fs/promises/_fs_readFile.ts
+++ b/std/node/_fs/promises/_fs_readFile.ts
@@ -1,16 +1,28 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
-import { FileOptions } from "../_fs_common.ts";
-import { MaybeEmpty } from "../../_utils.ts";
-
+import {
+  FileOptionsArgument,
+  BinaryOptionsArgument,
+  TextOptionsArgument,
+} from "../_fs_common.ts";
 import { readFile as readFileCallback } from "../_fs_readFile.ts";
 
 export function readFile(
   path: string | URL,
-  options?: FileOptions | string
-): Promise<MaybeEmpty<string | Uint8Array>> {
+  options: TextOptionsArgument
+): Promise<string>;
+export function readFile(
+  path: string | URL,
+  options?: BinaryOptionsArgument
+): Promise<Uint8Array>;
+export function readFile(
+  path: string | URL,
+  options?: FileOptionsArgument
+): Promise<string | Uint8Array> {
   return new Promise((resolve, reject) => {
     readFileCallback(path, options, (err, data): void => {
       if (err) return reject(err);
+      if (data == null)
+        return reject(new Error("Invalid state: data missing, but no error"));
       resolve(data);
     });
   });