Appease lint

Author: lithp

eth/db/chain.py

@@ -35,6 +35,7 @@
     GENESIS_PARENT_HASH,
 )
 from eth.exceptions import (
+    CanonicalHeadNotFound,
     HeaderNotFound,
     ReceiptNotFound,
     TransactionNotFound,

eth/db/header.py

@@ -1,5 +1,5 @@
 import functools
-from typing import Iterable, Tuple
+from typing import cast, Iterable, Tuple
 
 import rlp
 
@@ -89,7 +89,7 @@ def _get_canonical_head(cls, db: DatabaseAPI) -> BlockHeaderAPI:
     @classmethod
     def _get_canonical_head_hash(cls, db: DatabaseAPI) -> Hash32:
         try:
-            return db[SchemaV1.make_canonical_head_hash_lookup_key()]
+            return cast(Hash32, db[SchemaV1.make_canonical_head_hash_lookup_key()])
         except KeyError:
             raise CanonicalHeadNotFound("No canonical head set for this chain")