fix(nsis): correctly remove shortcut and only remove directory if its empty

Close #2381

Author: timfish

packages/electron-builder-lib/templates/nsis/uninstaller.nsh

@@ -38,11 +38,10 @@ Section "un.install"
     !ifndef DO_NOT_CREATE_START_MENU_SHORTCUT
       WinShell::UninstShortcut "$oldStartMenuLink"
 
+      Delete "$oldStartMenuLink"
       ReadRegStr $R1 SHELL_CONTEXT "${INSTALL_REGISTRY_KEY}" MenuDirectory
-      ${if} $R1 == ""
-        Delete "$oldStartMenuLink"
-      ${else}
-        RMDir /r "$SMPROGRAMS\$R1"
+      ${ifNot} $R1 == ""
+        RMDir "$SMPROGRAMS\$R1"
       ${endIf}
     !endif
   ${endIf}