test: tighten live media chunk helpers

src/auto-reply/chunk.test.ts

@@ -19,7 +19,6 @@ function expectFencesBalanced(chunks: string[]) {
 
 function requireChunk(chunks: string[], index: number): string {
   const chunk = chunks[index];
-  expect(chunk).toBeDefined();
   if (chunk === undefined) {
     throw new Error(`expected chunk ${index}`);
   }

src/scripts/test-live-media.test.ts

@@ -18,7 +18,6 @@ function requirePlanEntry(
   suiteId: string,
 ) {
   const entry = plan.find((candidate) => candidate.suite.id === suiteId);
-  expect(entry).toBeDefined();
   if (!entry) {
     throw new Error(`expected ${suiteId} run plan entry`);
   }