Fixes #3065 - Updating KB answers throws error 500 for agents without edit rights

app/policies/controllers/knowledge_base/categories_controller_policy.rb

@@ -2,6 +2,6 @@ class Controllers::KnowledgeBase::CategoriesControllerPolicy < Controllers::Know
   def show?
     return if user.permissions?('knowledge_base.editor')
 
-    record.klass.find(params[:id]).internal_content?
+    record.klass.find(record.params[:id]).internal_content?
   end
 end

spec/policies/controllers/knowledge_base/categories_controller_policy_spec.rb

@@ -0,0 +1,28 @@
+require 'rails_helper'
+
+describe Controllers::KnowledgeBase::CategoriesControllerPolicy do
+  include_context 'basic Knowledge Base'
+
+  subject { described_class.new(user, record) }
+
+  let(:record_class) { KnowledgeBase::CategoriesController }
+
+  let(:record) do
+    rec             = record_class.new
+    rec.action_name = action_name
+    rec.params      = params
+
+    rec
+  end
+
+  describe '#show?' do
+    let(:action_name) { :show }
+    let(:params)      { { id: internal_answer.category.id  } }
+
+    context 'with knowledge_base.reader permissions' do
+      let(:user) { create(:agent) }
+
+      it { is_expected.to permit_action(action_name) }
+    end
+  end
+end