PS-91 make isMacAppStore return true/false (#735)

* return false if undefined from isMacAppStore

* PS-91 use strict equality instead of null coalescing

Co-authored-by: Chad Scharf <3904944+cscharf@users.noreply.github.com>

Co-authored-by: Chad Scharf <3904944+cscharf@users.noreply.github.com>

electron/src/utils.ts

@@ -34,7 +34,7 @@ export function isMac() {
 }
 
 export function isMacAppStore() {
-  return isMac() && process.mas && process.mas === true;
+  return isMac() && process.mas === true;
 }
 
 export function isWindowsStore() {