txhash is not optionally returned from __fire - either it is or an ex…

…ception was raised.

atxm/machine.py

@@ -289,7 +289,7 @@ def __get_signer(self, address: str) -> LocalAccount:
             raise ValueError(f"Signer {address} not found")
         return signer
 
-    def __fire(self, tx: AsyncTx, msg: str) -> Optional[TxHash]:
+    def __fire(self, tx: AsyncTx, msg: str) -> TxHash:
         """
         Signs and broadcasts a transaction, handling RPC errors
         and internal state changes.