fix nil error

app/controllers/teachers_controller.rb

@@ -131,11 +131,7 @@ def update
       return
     end
 
-    # Attach the new files to the existing ones
-    params[:teacher][:more_files].each do |file|
-      @teacher.files.attach(file)
-    end
-
+    attach_new_files_if_any
     send_email_if_application_status_changed_and_email_resend_enabled
 
     if fail_to_update
@@ -278,6 +274,14 @@ def load_school
     end
   end
 
+  def attach_new_files_if_any
+    if params.dig(:teacher, :more_files).present?
+      params[:teacher][:more_files].each do |file|
+        @teacher.files.attach(file)
+      end
+    end
+  end
+
   def teacher_params
     teacher_attributes = [:first_name, :last_name, :school, :status, :snap,
                           :more_info, :personal_website, :education_level, :school_id, languages: [], files: [],