title: Solana Non-base58 character
body: <p>I'm trying to sign a transaction on solana with this piece of code:</p>
  <pre><code>                const txs = [];
  
                  const { recentBlockhash, instructions, feePayer } = tx;
  
                  const newTx = new SolTransaction({
                      feePayer,
                      recentBlockhash,
                  });
                  
                  for (const ins of instructions) {
                      newTx.add(ins);
                  }
                  
  
                  newTx.sign({ publicKey: this._signer.publicKey, secretKey: this._signer.secretKey });
                 
  
                  txs.push(newTx);
  
  </code></pre>
  <p>but for some reason when i sign the transaction i get this error:
  <code>Non-base58 character</code> any idea why?</p>