Fix crash with budgets with disabled current phase

There's an edge case where the current phase of the budget was disabled.
In this case, the application was crashing.

I'm not sure what we should do regarding this case. Is it OK to allow
disabling the current phase? Is it OK to allow selecting a disabled
phase as the current phase?

Since I'm not sure about it, for now I'm leaving it the same way it was.

Co-authored-by: Julian Herrero <microweb10@gmail.com>

app/components/admin/budgets/index_component.rb

@@ -19,7 +19,11 @@ class Admin::Budgets::IndexComponent < ApplicationComponent
     end
 
     def current_enabled_phase_number(budget)
-      budget.phases.enabled.order(:id).pluck(:kind).index(budget.phase) + 1
+      current_enabled_phase_index(budget) + 1
+    end
+
+    def current_enabled_phase_index(budget)
+      budget.phases.enabled.order(:id).pluck(:kind).index(budget.phase) || -1
     end
 
     def dates(budget)

spec/components/admin/budgets/index_component_spec.rb

@@ -0,0 +1,18 @@
+require "rails_helper"
+
+describe Admin::Budgets::IndexComponent, type: :component do
+  before do
+    allow(ViewComponent::Base).to receive(:test_controller).and_return("Admin::BudgetsController")
+    allow_any_instance_of(Admin::BudgetsController).to receive(:valid_filters).and_return(["all"])
+    allow_any_instance_of(Admin::BudgetsController).to receive(:current_filter).and_return("all")
+  end
+
+  it "displays current phase zero for budgets with no current phase" do
+    budget = create(:budget, :accepting, name: "Not enabled phase")
+    budget.phases.accepting.update!(enabled: false)
+
+    render_inline Admin::Budgets::IndexComponent.new(Budget.page(1))
+
+    expect(page.find("tr", text: "Not enabled phase")).to have_content "0/8"
+  end
+end