Error in then

A later .then receives the wrong value, an error appears in a surprising place, or a batch fails differently than expected. This is why `.catch` can handle JSON parsing or mapping failures after fetch.

Expecting a surrounding synchronous try/catch to catch later promise callbacks.

Return or await the promise chain so values and failures move through the flow intentionally.

return doWork()
  .then((value) => nextStep(value))
  .catch(handleError);

The console lane proves the visible order: boom. The active line and queues show why source order changed.

Write a focused unit test that asserts the resolved value or rejected path, then verify every branch returns or awaits its work.