chore: guard token airdrop channel service availability (#632)

Signed-off-by: advay-sinha <advaysinhaa@gmail.com>

Author: advay-sinha

CHANGELOG.md

@@ -13,6 +13,7 @@ This changelog is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.
 - add AccountRecordsQuery class
 
 ### Changed
+- chore: validate that token airdrop transactions require an available token service on the channel (#632) 
 
 - chore: fix type hint for TokenCancelAirdropTransaction pending_airdrops parameter
 - chore: Moved documentation file `common_issues.md` from `examples/sdk_developers/` to `docs/sdk_developers/` for unified documentation management (#516).

src/hiero_sdk_python/tokens/token_airdrop_transaction.py

@@ -219,7 +219,11 @@ def build_scheduled_body(self) -> SchedulableTransactionBody:
         return schedulable_body
 
     def _get_method(self, channel: _Channel) -> _Method:
+        token_service = channel.token
+        if token_service is None:
+            raise ValueError("Token service not available on channel")
+
         return _Method(
-            transaction_func=channel.token.airdropTokens,
+            transaction_func=token_service.airdropTokens,
             query_func=None
         )