Comment's added and fixed.

Pointer's checked for NULL before access and after memory allocations.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11499 6f19259b-4bc3-4df7-8a09-765794883524

ShellPkg/Library/UefiShellLevel2CommandsLib/Map.c

@@ -650,7 +650,7 @@ PerformMappingDisplay(
       &BufferSize,
       HandleBuffer);
   }
-  if (!EFI_ERROR(Status)) {
+  if (!EFI_ERROR(Status) && HandleBuffer != NULL) {
     //
     // Get the map name(s) for each one.
     //