pnpm use env does not check if already installed or not

[am05mhz]

if at first we run pnpm use env --global latest
then run pnpm use env --global 16
then for some reason need to go back to latest pnpm use env --global latest
if the latest version have not changed (eg still on 20), it will fail with error:

 Fetching Node.js 20.2.0 ...
 EEXIST  EEXIST: file already exists,

at least on windows

should be just change the env, or make a separate command for install and use, so that no need to install again, just change the env

[colinmollenhour]

Yes, I am using 8.5.1 and cannot switch to another node version, even as administrator:

[Gascognya]

me too, but not any time

[Rolanddoda]

@zkochan this is still an issue in 8.6.0