diff --git a/example_publisher/publisher.py b/example_publisher/publisher.py
index 0063e34..6dd5662 100644
--- a/example_publisher/publisher.py
+++ b/example_publisher/publisher.py
@@ -32,12 +32,20 @@ def __init__(self, config: Config) -> None:
         if not getattr(self.config, self.config.provider_engine):
             raise ValueError(f"Missing {self.config.provider_engine} config")
 
-        if self.config.provider_engine == "coin_gecko":
+        if (
+            self.config.provider_engine == "coin_gecko"
+            and config.coin_gecko is not None
+        ):
             self.provider = CoinGecko(config.coin_gecko)
-        elif self.config.provider_engine == "pyth_replicator":
+        elif (
+            self.config.provider_engine == "pyth_replicator"
+            and config.pyth_replicator is not None
+        ):
             self.provider: Provider = PythReplicator(config.pyth_replicator)
         else:
-            raise ValueError(f"Unknown provider {self.config.provider_engine}")
+            raise ValueError(
+                f"Unknown provider {self.config.provider_engine}, possibly the env variables is not set."
+            )
 
         self.pythd: Pythd = Pythd(
             address=config.pythd.endpoint,
diff --git a/example_publisher/pythd.py b/example_publisher/pythd.py
index 5c8a7de..e9ee423 100644
--- a/example_publisher/pythd.py
+++ b/example_publisher/pythd.py
@@ -2,8 +2,8 @@
 from dataclasses import dataclass, field
 import sys
 import traceback
-from dataclasses_json import config, dataclass_json
-from typing import Awaitable, Callable, List
+from dataclasses_json import config, DataClassJsonMixin
+from typing import Any, Callable, Coroutine, List
 from structlog import get_logger
 from jsonrpc_websocket import Server
 
@@ -15,22 +15,19 @@
 TRADING = "trading"
 
 
-@dataclass_json
 @dataclass
-class Price:
+class Price(DataClassJsonMixin):
     account: str
     exponent: int = field(metadata=config(field_name="price_exponent"))
 
 
-@dataclass_json
 @dataclass
-class Metadata:
+class Metadata(DataClassJsonMixin):
     symbol: str
 
 
-@dataclass_json
 @dataclass
-class Product:
+class Product(DataClassJsonMixin):
     account: str
     metadata: Metadata = field(metadata=config(field_name="attr_dict"))
     prices: List[Price] = field(metadata=config(field_name="price"))
@@ -38,14 +35,16 @@ class Product:
 
 class Pythd:
     def __init__(
-        self, address: str, on_notify_price_sched: Callable[[SubscriptionId], Awaitable]
+        self,
+        address: str,
+        on_notify_price_sched: Callable[[SubscriptionId], Coroutine[Any, Any, None]],
     ) -> None:
         self.address = address
-        self.server: Server = None
+        self.server: Server
         self.on_notify_price_sched = on_notify_price_sched
         self._tasks = set()
 
-    async def connect(self) -> Server:
+    async def connect(self):
         self.server = Server(self.address)
         self.server.notify_price_sched = self._notify_price_sched
         task = await self.server.ws_connect()
diff --git a/example_publisher/tests/test_pyth_replicator_manual_aggregate.py b/example_publisher/tests/test_pyth_replicator_manual_aggregate.py
index b0d2a9c..a003744 100644
--- a/example_publisher/tests/test_pyth_replicator_manual_aggregate.py
+++ b/example_publisher/tests/test_pyth_replicator_manual_aggregate.py
@@ -1,9 +1,10 @@
 import random
+from typing import List
 from example_publisher.providers.pyth_replicator import manual_aggregate
 
 
 def test_manual_aggregate_works():
-    prices = [1, 2, 3, 4, 5, 6, 8, 10, 12, 14]
+    prices: List[float] = [1, 2, 3, 4, 5, 6, 8, 10, 12, 14]
     random.shuffle(prices)
 
     agg_price, agg_confidence_interval = manual_aggregate(prices)