Undefined from an async function is almost always one of three bugs.
Diagnose in this order:

1. MISSING RETURN INSIDE .then / callback
   const get = async () => { fetchData().then(d => d.value) }
   The arrow returns nothing; the .then result is discarded. Fix: await
   and return, or return the chain.

2. FORGOTTEN await ON A NESTED CALL
   const x = getUser()  // returns a Promise, not a user
   x.name is undefined because x is a pending Promise. await it.

3. forEach WITH async — the silent one
   arr.forEach(async i => { results.push(await f(i)) })
   forEach ignores the returned Promises; the function moves on before
   any push happens. This is the single most common cause.
   Fix: for...of with await, or Promise.all(arr.map(f)).

MODERN FIX FOR #3
  const results = await Promise.all(arr.map(f))
  Runs them concurrently AND waits for all — forEach does neither.

THE DEBUGGING MOVE
Log typeof at the return: a "object" that's actually a Promise (has a
.then) tells you it's a missing await, not a missing value. A genuine
undefined tells you it's a missing return.

Paste the function and I'll point at the exact line.