Add pointer check for NULL before dereference it.

Signed-off-by: ydong10
Reviewed-by: rsun3, lgao4

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12472 6f19259b-4bc3-4df7-8a09-765794883524

MdeModulePkg/Universal/SetupBrowserDxe/InputHandler.c

@@ -1122,6 +1122,7 @@ GetSelectionInputPopUp (
       Link = GetNextNode (&Question->OptionListHead, Link);
 
       StringPtr = GetToken (OneOfOption->Text, MenuOption->Handle);
+      ASSERT (StringPtr != NULL);
       //
       // If the string occupies multiple lines, truncate it to fit in one line,
       // and append a "..." for indication.