check _request_information_cache value is a dict before .get-ing from it

Author: pacrob

Diff for: newsfragments/3642.bugfix.rst

@@ -0,0 +1 @@
+Checks that ``PersistentConnectionProvider`` response cache value is a dict before attempting to access it like one.

Diff for: tests/core/providers/test_websocket_provider.py

@@ -510,3 +510,19 @@ async def test_websocket_provider_raises_errors_from_cache_not_tied_to_a_request
         with pytest.raises(Web3RPCError, match="Request shutdown"):
             await asyncio.sleep(0.1)
             await async_w3.eth.block_number
+
+
+@pytest.mark.asyncio
+async def test_raise_stray_errors_from_cache_handles_list_response():
+    provider = WebSocketProvider("ws://mocked")
+    _mock_ws(provider)
+
+    bad_response = [
+        {"id": None, "jsonrpc": "2.0", "error": {"code": 21, "message": "oops"}}
+    ]
+    provider._request_processor._request_response_cache._data["bad_key"] = bad_response
+
+    try:
+        provider._raise_stray_errors_from_cache()
+    except Exception as e:
+        pytest.fail(f"{e}")

Diff for: web3/providers/persistent/persistent.py

@@ -318,17 +318,16 @@ def _raise_stray_errors_from_cache(self) -> None:
             for (
                 response
             ) in self._request_processor._request_response_cache._data.values():
-                request = (
-                    self._request_processor._request_information_cache.get_cache_entry(
+                if isinstance(response, dict):
+                    request = self._request_processor._request_information_cache.get_cache_entry(  # noqa: E501
                         generate_cache_key(response["id"])
                     )
-                )
-                if "error" in response and request is None:
-                    # if we find an error response in the cache without a corresponding
-                    # request, raise the error
-                    validate_rpc_response_and_raise_if_error(
-                        response, None, logger=self.logger
-                    )
+                    if "error" in response and request is None:
+                        # if we find an error response in the cache without a
+                        # corresponding request, raise the error
+                        validate_rpc_response_and_raise_if_error(
+                            cast(RPCResponse, response), None, logger=self.logger
+                        )
 
     async def _message_listener(self) -> None:
         self.logger.info(