Panic if no fee-payer found via Message::new() (#10050)

automerge

sdk/src/transaction.rs

@@ -80,7 +80,7 @@ impl std::fmt::Display for TransactionError {
 }
 
 /// An atomic transaction
-#[derive(Debug, PartialEq, Eq, Clone, Serialize, Deserialize)]
+#[derive(Debug, PartialEq, Default, Eq, Clone, Serialize, Deserialize)]
 pub struct Transaction {
     /// A set of digital signatures of `account_keys`, `program_ids`, `recent_blockhash`, and `instructions`, signed by the first
     /// signatures.len() keys of account_keys