lib: remove useless type check on fs

recursive always is the type boolean

for an example

https://github.com/nodejs/node/blob/eca71e5a0c4b5e4357d8e871a5dc46b10e9bd1f1/lib/fs.js#L766-L773

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines