type es un campo reservado

app/controllers/readings_controller.rb

@@ -49,7 +49,9 @@ class ReadingsController < ActionController::API
 
   # Procesa los parámetros de un sensor
   def sensor_params(sensor)
-    sensor.permit(:timestamp, :type, :value, :unit, :error)
+    sensor.permit(:timestamp, :type, :value, :unit, :error).tap do |p|
+      p[:local_type] = p.delete :type
+    end
   end
 end
 

db/migrate/20220303170706_change_type.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class ChangeType < ActiveRecord::Migration[6.1]
+  def change
+    rename_column :sensors, :type, :local_type
+  end
+end