message: chore: revert error stringification
diff: @@ -18,7 +18,7 @@ export class Rpc {
  try {
  this.sendMessage({ seqNum, result: await this.methods[name](...args) })
  } catch (ex) {
  - this.sendMessage({ seqNum, exception: ex === undefined ? 'error' : ex.toString() })
  + this.sendMessage({ seqNum, exception: ex === undefined ? 'error' : ex })
  }
  })()
  }
  