client: Make sending a tx not panic and instead return an Error when signing fails

CHANGELOG.md

@@ -63,6 +63,7 @@ The minor version will be incremented upon a breaking change and the patch versi
 
 ### Breaking
 
+- client: Make sending a tx not panic and instead return an Error when signing fails ([#3865](https://github.com/solana-foundation/anchor/pull/3865)).
 - spl: Update SPL dependencies to latest compatible versions ([#3860](https://github.com/solana-foundation/anchor/pull/3860)).
 - cli: Replace `anchor verify` to use `solana-verify` under the hood, adding automatic installation via AVM, local path support, and future-proof argument passing ([#3768](https://github.com/solana-foundation/anchor/pull/3768)).
 - cli: Upload IDL by default with an option to skip ((#3863)[https://github.com/solana-foundation/anchor/pull/3863]).

client/src/lib.rs

@@ -500,6 +500,8 @@ pub enum ClientError {
     LogParseError(String),
     #[error(transparent)]
     IOError(#[from] std::io::Error),
+    #[error("{0}")]
+    SignerError(#[from] SignerError),
 }
 
 pub trait AsSigner {
@@ -604,7 +606,7 @@ impl<C: Deref<Target = impl Signer> + Clone, S: AsSigner> RequestBuilder<'_, C,
         self
     }
 
-    pub fn instructions(&self) -> Result<Vec<Instruction>, ClientError> {
+    pub fn instructions(&self) -> Vec<Instruction> {
         let mut instructions = self.instructions.clone();
         if let Some(ix_data) = &self.instruction_data {
             instructions.push(Instruction {
@@ -614,32 +616,26 @@ impl<C: Deref<Target = impl Signer> + Clone, S: AsSigner> RequestBuilder<'_, C,
             });
         }
 
-        Ok(instructions)
+        instructions
     }
 
     fn signed_transaction_with_blockhash(
         &self,
         latest_hash: Hash,
     ) -> Result<Transaction, ClientError> {
-        let instructions = self.instructions()?;
         let signers: Vec<&dyn Signer> = self.signers.iter().map(|s| s.as_signer()).collect();
         let mut all_signers = signers;
         all_signers.push(&*self.payer);
 
-        let tx = Transaction::new_signed_with_payer(
-            &instructions,
-            Some(&self.payer.pubkey()),
-            &all_signers,
-            latest_hash,
-        );
+        let mut tx = self.transaction();
+        tx.try_sign(&all_signers, latest_hash)?;
 
         Ok(tx)
     }
 
-    pub fn transaction(&self) -> Result<Transaction, ClientError> {
-        let instructions = &self.instructions;
-        let tx = Transaction::new_with_payer(instructions, Some(&self.payer.pubkey()));
-        Ok(tx)
+    pub fn transaction(&self) -> Transaction {
+        let instructions = &self.instructions();
+        Transaction::new_with_payer(instructions, Some(&self.payer.pubkey()))
     }
 
     async fn signed_transaction_internal(&self) -> Result<Transaction, ClientError> {