fix(streams): tighten stream typings and guard optional runtime paths for duplex and wrapper utilities

test/test.webduplexstream.both.ts

@@ -1,13 +1,13 @@
-import { expect, tap } from '@push.rocks/tapbundle';
+import { expect, tap } from '@git.zone/tstest/tapbundle';
 import { WebDuplexStream } from '../ts_web/index.js';
 
 // Helper: collect all chunks from a readable
 async function collectAll<T>(reader: ReadableStreamDefaultReader<T>): Promise<T[]> {
   const results: T[] = [];
   while (true) {
-    const { value, done } = await reader.read();
-    if (done) break;
-    results.push(value);
+    const result = await reader.read();
+    if (result.done) break;
+    results.push(result.value);
   }
   return results;
 }
@@ -70,6 +70,9 @@ tap.test('WebDuplexStream: fromUInt8Array should produce data', async () => {
 
   const { value } = await reader.read();
   expect(value).toBeTruthy();
+  if (!value) {
+    throw new Error('Expected fromUInt8Array to produce data');
+  }
   expect(value.length).toEqual(5);
 });