Comment puis-je résoudre cette erreur sur == how can I resolve this error on

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PHP

CodeIgniter

Je reçois cette erreur:
Une erreur PHP a été rencontrée
Severity: Avertissement
Message: Undefined array key "id"
Nom du fichier: controllers/patient.php
Numéro de la ligne: 353

voici le code:

  1   if (empty($id)) {     // Adding New Patient
  2                  if ($this->ion_auth->email_check($email)) {
  3                      $this->session->set_flashdata('feedback', 'Cette adresse email est déjà enregistré dans la base données');
  4                      redirect('patient/addNewView');
  5                  } else {
  6                      $dfg = 5;
  7                      $this->ion_auth->register($username, $password, $email, $dfg);
  8  //                    $ion_user_id=this->db-get_where('users', array('email'=> $email))->row()['id'];
  9                      $ion_user_id = $this->db->get_where('users', array('email' => $email))->row()['id'];
 10                      $this->patient_model->insertPatient($data);
 11                      $patient_user_id = $this->db->get_where('patient', array('email' => $email))->row()->id;
 12                      $id_info = array('ion_user_id' => $ion_user_id);
 13                      $this->patient_model->updatePatient($patient_user_id, $id_info);
 14                      $this->hospital_model->addHospitalIdToIonUser($ion_user_id, $this->hospital_id);
 15  
 16                      if (!empty($sms)) {
 17                          $this->sms->sendSmsDuringPatientRegistration($patient_user_id);
 18                      }
 19  
 20  
 21                      $this->session->set_flashdata('feedback', 'Ajouté');
 22                  }
 23                  //    }
 24              } else { // Updating Patient
 25                  $ion_user_id = $this->db->get_where('patient', array('id' => $id))->row()->ion_user_id;
 26                  if (empty($password)) {
 27                      $password = $this->db->get_where('users', array('id' => $ion_user_id))->row()->password;
 28                  } else {
 29                      $password = $this->ion_auth_model->hash_password($password);
 30                  }
 31                  $this->patient_model->updateIonUser($username, $email, $password, $ion_user_id);
 32                  $this->patient_model->updatePatient($id, $data);
 33                  $this->session->set_flashdata('feedback', 'Modifié');
 34              }
 35              // Loading View
 36              if (!empty($redirect)) {
 37                  redirect('finance/addPaymentView');
 38              } else {
 39                  redirect('patient');
 40              }
 41          }
 42      }

Translation:
How can I resolve this error on

I'm getting this error:
A PHP error has been encountered
Severity: Warning
Message: Undefined array key "id"
File name: controllers/patient.php
Line Number: 353

What I have tried:

Cette erreur apparait lorsque j'essaie d'enregistrer un nouveau patient

Translation:
This error appears when I try to register a new patient