Core: ensure slot_data and er_hint_info are only base data types (#5144)

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Co-authored-by: Doug Hoskisson <beauxq@users.noreply.github.com>

test/general/test_implemented.py

@@ -1,7 +1,7 @@
 import unittest
 
 from Fill import distribute_items_restrictive
-from NetUtils import encode
+from NetUtils import convert_to_base_types
 from worlds.AutoWorld import AutoWorldRegister, call_all
 from worlds import failed_world_loads
 from . import setup_solo_multiworld
@@ -47,7 +47,7 @@ class TestImplemented(unittest.TestCase):
                 call_all(multiworld, "post_fill")
                 for key, data in multiworld.worlds[1].fill_slot_data().items():
                     self.assertIsInstance(key, str, "keys in slot data must be a string")
-                    self.assertIsInstance(encode(data), str, f"object {type(data).__name__} not serializable.")
+                    convert_to_base_types(data)  # only put base data types into slot data
 
     def test_no_failed_world_loads(self):
         if failed_world_loads: