The docs mention:
// Finished the workbook.
workbook.commit().then(function() { /* the stream has been written */ });

I used it like:
book.commit().then(() => response.end())

After I upgraded types/exceljs to ^0.5.2 typescript warned me for commit() not giving back a promise.

So I changed it to:
book.commit();
response.end();
After this things went wrong because response.end() was breaking the stream too early.
After removing response.end() it worked fine. Perhaps commit() called response,end() itself.

So 3 questions:

• Need the docs be adjusted: commit() no longer brings a response?
• Or is types/exceljs wrong here?
• Does commit() really end the response?