fdfd59a#diff-9290f26e7bf7a9fe9720ea49c795b8f292c16efd2093925f68af2aa9bd411b2fR6 requires @swc/core to be installed, to properly get the type.
Either add swc/core as a regular dependency or change that type should be done.

My library uses tsup programmatically, and now it doesn't compile anymore.