Fix fetch body type error by returning ArrayBuffer from compression helper

src/client/LocalServer.ts

@@ -235,7 +235,7 @@ export class LocalServer {
   }
 }
 
-async function compress(data: string): Promise<Uint8Array> {
+async function compress(data: string): Promise<ArrayBuffer> {
   const stream = new CompressionStream("gzip");
   const writer = stream.writable.getWriter();
   const reader = stream.readable.getReader();
@@ -264,5 +264,5 @@ async function compress(data: string): Promise<Uint8Array> {
     offset += chunk.length;
   }
 
-  return compressedData;
+  return compressedData.buffer;
 }