fix: timeout error not show in progress (#96)

because previously was not properly encoded but this enqueue can be
removed since the chat will be refreshed with db data
<img width="982" alt="image"
src="https://github.com/landing-ai/vision-agent-ui/assets/132986242/cfd0bbd5-e1e7-4159-8a4f-14c0225a55fa">

app/api/vision-agent/route.ts

@@ -214,11 +214,6 @@ export const POST = withLogging(
           if (lines.length === 0) {
             if (Date.now() - time > TIMEOUT_MILI_SECONDS) {
               results.push(FINAL_TIMEOUT_ERROR);
-              // https://github.com/vercel/ai/blob/f7002ad2c5aa58ce6ed83e8d31fe22f71ebdb7d7/packages/ui-utils/src/stream-parts.ts#L62
-              controller.enqueue(
-                '2:' +
-                  encoder.encode(JSON.stringify(FINAL_TIMEOUT_ERROR) + '\n'),
-              );
               return { done: true, reason: 'timeout' };
             }
           } else {
@@ -240,6 +235,7 @@ export const POST = withLogging(
               return { done: true, reason: 'api_error', error };
             } else if (parsedMsg) {
               results.push(parsedMsg);
+              // https://github.com/vercel/ai/blob/f7002ad2c5aa58ce6ed83e8d31fe22f71ebdb7d7/packages/ui-utils/src/stream-parts.ts#L62
               controller.enqueue(
                 encoder.encode('2:' + JSON.stringify([parsedMsg]) + '\n'),
               );