🐛 BUG: D1 export throws cryptic error when passed directory instead of file

[irvinebroque]

Which Cloudflare product(s) does this pertain to?

D1

What versions are you using?

Wrangler 3.99.0

What operating system and version are you using?

Mac latest

Please provide a link to a minimal reproduction

No response

Describe the Bug

When you try to export a D1 DB, but you provide --output with a directory rather than a filename:

npx wrangler@latest d1 export db-name --remote --output ./

...you get an error that is cryptic:

✘ [ERROR] EISDIR: illegal operation on a directory, open './'

This error is pretty easily googleable, but it still feels like we could do better — and actually validate that what was provided is a filename, not a filepath, and throw a more helpful and specific input validation error.

This seesm particularly important given that otherwise, we show this:

If you think this is a bug then please create an issue at https://github.com/cloudflare/workers-sdk/issues/new/choose
✔ Would you like to report this error to Cloudflare? … yes

Which kind of suggests that this is a bug, an unknown/unhandled case.

Please provide any relevant error logs

No response