Fixed type of encoding in stream write

Author: TheSpyder

lib/js/test/atomic/Stream.test.bs.js

@@ -240,13 +240,13 @@ module Writable = {
     ~writev: @this (
       objStream<'w>,
       ~data: array<chunk<'w>>,
-      ~encoding: StringEncoding.t,
+      ~encoding: Js.null<StringEncoding.t>,
       ~callback: (~error: option<Js.Exn.t>) => unit,
     ) => unit=?,
     ~write: @this (
       objStream<'w>,
       ~data: 'w,
-      ~encoding: StringEncoding.t,
+      ~encoding: Js.null<StringEncoding.t>,
       ~callback: (~error: option<Js.Exn.t>) => unit,
     ) => unit,
     unit,

src/Stream.res

@@ -86,7 +86,7 @@ zoraBlock("Stream.Writable", t => {
                   Js.typeof(cb),
                 ))
               }
-              t->equal(actual, Some(("Writable", "number", StringEncoding.utf8, "function")), "")
+              t->equal(actual, Some(("Writable", "number", Js.null, "function")), "")
 
               resolve(. ())
             },