system/Database/MySQLi/Connection.php
public function error(): array
	{
		if (! empty($this->mysqli->connect_errno))
		{
			return [
				'code'    => $this->mysqli->connect_errno,
				'message' => $this->mysqli->connect_error,
			];
		}

		return [
			'code'    => $this->connID->errno,
			'message' => $this->connID->error,
		];
	}
public function error(): array
	{
		if (! empty($this->mysqli->connect_errno))
		{
			return [
				'code'    => $this->mysqli->connect_errno,
				'message' => $this->mysqli->connect_error,
			];
		}

		return [
			'code'    => $this->connID->errno,
			'message' => $this->connID->error,
		];
	}
Returns the last error code and message.

Must return an array with keys 'code' and 'message':

return ['code' => null, 'message' => null);

@return array