fix: optimization: PVS-Studio warning V815

The 'empty()' method is more efficient for checking if a string is empty compared to comparing it with an empty string literal.

The default constructor 'std::wstring()' is more efficient for creating an empty string compared to using a string literal.

The 'clear()' method is more efficient for clearing a std::wstring compared to assigning it an empty string literal.

Reported by: PVS-Studio
Signed-off-by: Vyacheslav Ivanov <islavaivanov76@gmail.com>

src/logic/scripting/scripting_functional.cpp

@@ -66,7 +66,7 @@ wstringsupplier scripting::create_wstring_supplier(
             auto str = lua::require_wstring(L, -1); lua::pop(L);
             return str;
         }
-        return std::wstring(L"");
+        return std::wstring();
     };
 }