lib: return directly from packageMainCache

This commit updates readPackage to return directly when calling
packageMainCache instead of storing the result in a local var
and returning later.
PR-URL: #20591
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

Author: danbev

lib/internal/modules/cjs/loader.js

@@ -153,13 +153,12 @@ function readPackage(requestPath) {
 }
 
 try{
-varpkg=packageMainCache[requestPath]=JSON.parse(json).main;
+returnpackageMainCache[requestPath]=JSON.parse(json).main;
 }catch(e){
 e.path=jsonPath;
 e.message='Error parsing '+jsonPath+': '+e.message;
 throwe;
 }
-returnpkg;
 }
 
 functiontryPackage(requestPath,exts,isMain){