Fix credential check in the standalone sender

The boolean expression rejected a valid login/password configuration
whenever no token was set, and left `client` unbound when neither branch
assigned it. Require a base URL plus either a token or a complete
login/password pair.

Also fix two log calls that used unformatted "{...}" placeholders.

adapter.py

@@ -1210,25 +1210,28 @@ async def hermes_standalone_sender_fn(
     """
 
     chatto_config: ChattoConfiguration = ChattoConfiguration(pconfig=pconfig)
-    
-    # Create a temporary client for standalone sending
-    client: ChattoClient
 
-    if not chatto_config.base_url.value or (not (chatto_config.login.value or not chatto_config.password.value) or not chatto_config.token.value):
+    # Create a temporary client for standalone sending — we need a base URL plus
+    # either a token or a full login/password pair.
+    has_credentials = bool(
+        chatto_config.token.value
+        or (chatto_config.login.value and chatto_config.password.value)
+    )
+    if not chatto_config.base_url.value or not has_credentials:
         return SendResult(success=False, error="Chatto: base URL or credentials missing")
-    
-    try: 
+
+    client: ChattoClient
+    try:
         if chatto_config.token.value:
             client = ChattoClient(base_url=chatto_config.base_url.value, token=chatto_config.token.value)
         else:
-            if chatto_config.login.value and chatto_config.password.value:
-                client = await ChattoClient.login(
-                    base_url=chatto_config.base_url.value, login=chatto_config.login.value, password=chatto_config.password.value,
-                )
-    except (Exception, ValueError) as exc:
+            client = await ChattoClient.login(
+                base_url=chatto_config.base_url.value,
+                login=chatto_config.login.value,
+                password=chatto_config.password.value,
+            )
+    except Exception as exc:
         return SendResult(success=False, error=f"Chatto login failed: {exc}")
-    finally:
-        logger.debug("Chatto standalone client: {client}")
 
     try:
         kwargs: Dict[str, Any] = {}
@@ -1245,7 +1248,9 @@ async def hermes_standalone_sender_fn(
         try:
             await client.close()
         except Exception as exc:
-            logger.error("Chatto standalone: error closing short-lived client. Perhaps already closed. {exc}")
+            logger.error(
+                "Chatto standalone: error closing short-lived client (perhaps already closed): %s", exc,
+            )
 
 
 def hermes_validate_config(config: PlatformConfig) -> bool: