Avoid textproto crashing on empty reader (denoland/deno_std#50)

Original: https://github.com/denoland/deno_std/commit/9eb6aa5fd9da9da9cd2b96a5199cf9b9128fd456

2 files changed, 10 insertions, 2 deletions

diff --git a/net/textproto.ts b/net/textproto.ts
index 342d74b33..832299e1c 100644
--- a/net/textproto.ts
+++ b/net/textproto.ts
@@ -118,11 +118,12 @@ export class TextProtoReader {
 
   async readLineSlice(): Promise<[Uint8Array, BufState]> {
     // this.closeDot();
-    let line: null | Uint8Array;
+    let line: Uint8Array;
     while (true) {
       let [l, more, err] = await this.r.readLine();
       if (err != null) {
-        return [null, err];
+        // Go's len(typed nil) works fine, but not in JS
+        return [new Uint8Array(0), err];
       }
       // Avoid the copy if the first call produced a full line.
       if (line == null && !more) {
diff --git a/net/textproto_test.ts b/net/textproto_test.ts
index ad7e6a2c4..3af21247a 100644
--- a/net/textproto_test.ts
+++ b/net/textproto_test.ts
@@ -93,3 +93,10 @@ test(async function textprotoAppend() {
   const joined = append(u1, u2);
   assertEqual(dec.decode(joined), "Hello World");
 });
+
+test(async function textprotoReadEmpty() {
+  let r = reader("");
+  let [m, err] = await r.readMIMEHeader();
+  // Should not crash!
+  assertEqual(err, "EOF");
+});