Development speed is one. If the author were more familiar with JavaScript (e.g. knowing what const does) it might have gone faster. Using TypeScript should erase the development time delta due to static types.
If you're creating a frontend web app to go along with it there are others, such as reduced context–switching and using fewer tools.
Frankly, a sample size of one is incredibly weak evidence that it's faster to develop using one technology than another. If you glance through the author's Twitter/GitHub it's also clear that he works with Rust significantly more than he does with Node, which makes this particular sample even more suspect.
Indeed I am working primarily on Rust now, though I used to write Node 2 years ago and this is one of pitfalls where I would like to rely on compiler. It was just one issue which could been easily detected. Some debugging time was spent aligning SQL query parameters and mapping selected fields to the output type - the problem is that when there is some misalignment node does not raise exception, rather just passing undefined value. That's what takes time, to realize that there is a problem and then find the issue.
Agreed that in general expert in node probably won't hit such issues, though how many experts do we have. Type safety checks, including runtime checks, are actually making technology more adoptable. It does not seem that typescript can do that well though.
If you're creating a frontend web app to go along with it there are others, such as reduced context–switching and using fewer tools.
Frankly, a sample size of one is incredibly weak evidence that it's faster to develop using one technology than another. If you glance through the author's Twitter/GitHub it's also clear that he works with Rust significantly more than he does with Node, which makes this particular sample even more suspect.