fix: normalize int fields, align amount sentinel, fail-fast malformed airdrop entries

Signed-off-by: Mounil Kanakhara <mounilkankhara@gmail.com>

Author: Mounil2005

src/hiero_sdk_python/contract/contract_execute_transaction.py

@@ -170,8 +170,8 @@ def _from_protobuf(cls, transaction_body, body_bytes: bytes, sig_map):
             body = transaction_body.contractCall
             if body.HasField("contractID"):
                 transaction.contract_id = ContractId._from_proto(body.contractID)
-            transaction.gas = body.gas if body.gas else None
-            transaction.amount = body.amount if body.amount else None
+            transaction.gas = body.gas
+            transaction.amount = body.amount
             transaction.function_parameters = body.functionParameters if body.functionParameters else None
         return transaction
 

src/hiero_sdk_python/contract/ethereum_transaction.py

@@ -130,7 +130,7 @@ def _from_protobuf(cls, transaction_body, body_bytes: bytes, sig_map):
             transaction.ethereum_data = body.ethereum_data if body.ethereum_data else None
             if body.HasField("call_data"):
                 transaction.call_data = FileId._from_proto(body.call_data)
-            transaction.max_gas_allowed = body.max_gas_allowance if body.max_gas_allowance else None
+            transaction.max_gas_allowed = body.max_gas_allowance
         return transaction
 
     def _get_method(self, channel: _Channel) -> _Method:

src/hiero_sdk_python/tokens/token_airdrop_transaction.py

@@ -70,11 +70,11 @@ def _from_protobuf(cls, transaction_body, body_bytes: bytes, sig_map):
         if transaction_body.HasField("tokenAirdrop"):
             for transfer in transaction_body.tokenAirdrop.token_transfers:
                 if not transfer.HasField("token"):
-                    continue
+                    raise ValueError("Malformed TokenAirdropTransactionBody: token_transfer missing token field")
                 token_id = TokenId._from_proto(transfer.token)
                 for t in transfer.transfers:
                     if not t.HasField("accountID"):
-                        continue
+                        raise ValueError("Malformed TokenAirdropTransactionBody: fungible transfer missing accountID")
                     account_id = AccountId._from_proto(t.accountID)
                     expected_decimals = (
                         transfer.expected_decimals.value if transfer.HasField("expected_decimals") else None
@@ -84,7 +84,9 @@ def _from_protobuf(cls, transaction_body, body_bytes: bytes, sig_map):
                     )
                 for n in transfer.nftTransfers:
                     if not n.HasField("senderAccountID") or not n.HasField("receiverAccountID"):
-                        continue
+                        raise ValueError(
+                            "Malformed TokenAirdropTransactionBody: NFT transfer missing sender or receiver"
+                        )
                     sender_id = AccountId._from_proto(n.senderAccountID)
                     receiver_id = AccountId._from_proto(n.receiverAccountID)
                     transaction.nft_transfers[token_id].append(

src/hiero_sdk_python/tokens/token_burn_transaction.py

@@ -167,7 +167,7 @@ def _from_protobuf(cls, transaction_body, body_bytes: bytes, sig_map):
             body = transaction_body.tokenBurn
             if body.HasField("token"):
                 transaction.token_id = TokenId._from_proto(body.token)
-            transaction.amount = body.amount if body.amount else None
+            transaction.amount = body.amount
             transaction.serials = list(body.serialNumbers)
         return transaction
 

tests/unit/token_burn_transaction_test.py

@@ -218,4 +218,4 @@ def test_from_bytes_nft(mock_account_ids):
     assert isinstance(reconstructed, TokenBurnTransaction)
     assert reconstructed.token_id == token_id_1
     assert list(reconstructed.serials) == serials
-    assert reconstructed.amount is None
+    assert reconstructed.amount == 0