Appium Doctor gives exception

info AppiumDoctor ### Diagnostic starting ###
WARN AppiumDoctor :heavy_multiplication_x: Xcode is NOT installed!
[Error: Could not detect Mac OS X Version: Error: Command ‘sw_vers -productVersion’ errored out: Error: spawn sw_vers ENOENT
at exports._errnoException (util.js:890:11)
at Process.ChildProcess._handle.onexit (internal/child_process.js:182:32)
at onErrorNT (internal/child_process.js:348:16)
at _combinedTickCallback (internal/process/next_tick.js:74:11)
at process._tickCallback (internal/process/next_tick.js:98:9)
at Function.Module.runMain (module.js:449:11)
at startup (node.js:146:18)
at node.js:404:3]