fix potion issues

1. logical error when to use default_potion()
2. resolve the 'object backing the pointer ' warning for potion_view

Author: sorens

engine/player/player.cpp

@@ -12322,20 +12322,12 @@ std::unique_ptr<expr_t> player_t::create_expression( util::string_view expressio
 
   if ( splits.size() == 2 && splits[ 0 ] == "potion" )
   {
-    std::string_view potion_view;
+    std::string potion_name = potion_str.empty() ? default_potion() : potion_str;
 
-    if ( !potion_str.empty() )
-    {
-      potion_view = potion_str;
-    }
-    else if ( default_potion().empty() )
-    {
-      potion_view = default_potion();
-    }
-    else
-    {
+    if ( potion_name.empty() )
       return expr_t::create_constant( expression_str, false );
-    }
+
+    std::string_view potion_view = potion_name;
 
     if ( util::str_compare_ci( potion_view, splits[ 1 ] ) )
       return expr_t::create_constant( expression_str, true );