chore(internal): streaming refactors (#1261)

Author: stainless-app[bot]

Diff for: src/streaming.ts

@@ -38,9 +38,7 @@ export class Stream<Item> implements AsyncIterable<Item> {
           if (sse.data.startsWith('[DONE]')) {
             done = true;
             continue;
-          }
-
-          if (sse.event === null) {
+          } else {
             let data;
 
             try {