Refactor sparkline error handling and improve series pre-loading

- Added pre-loading of series in AccountableSparklinesController and AccountsController to catch errors before rendering.
- Updated the accounts view to use the pre-loaded sparkline series variable.
- Adjusted the test for graceful handling of errors in the sparkline series method.

This enhances the robustness of the sparkline feature and improves error visibility in the UI.

test/controllers/accountable_sparklines_controller_test.rb

@@ -0,0 +1,21 @@
+require "test_helper"
+
+class AccountableSparklinesControllerTest < ActionDispatch::IntegrationTest
+  setup do
+    sign_in @user = users(:family_admin)
+  end
+
+  test "should get show for depository" do
+    get accountable_sparkline_url("depository")
+    assert_response :success
+  end
+
+  test "should handle sparkline errors gracefully" do
+    # Mock an error in the balance_series method
+    Balance::ChartSeriesBuilder.any_instance.stubs(:balance_series).raises(StandardError.new("Test error"))
+
+    get accountable_sparkline_url("depository")
+    assert_response :success
+    assert_match /Error/, response.body
+  end
+end

test/controllers/accounts_controller_test.rb

@@ -27,11 +27,11 @@ class AccountsControllerTest < ActionDispatch::IntegrationTest
   end
 
   test "should handle sparkline errors gracefully" do
-    # Mock an error in the sparkline_series method
-    @account.stubs(:sparkline_series).raises(StandardError.new("Test error"))
+  # Mock an error in the balance_series method to bypass the rescue in sparkline_series
+  Balance::ChartSeriesBuilder.any_instance.stubs(:balance_series).raises(StandardError.new("Test error"))
 
-    get sparkline_account_url(@account)
-    assert_response :success
-    assert_match /Error/, response.body
-  end
+  get sparkline_account_url(@account)
+  assert_response :success
+  assert_match /Error/, response.body
+end
 end