Component renders "" (blank) when an error is raised during the render phase

[mjacobus]

Steps to reproduce

Render a component from a controller

class MyBrokenComponent < ViewComponent::Base
  erb_template <<-ERB
    foo <% raise_an_error %> bar
  ERB

  def raise_an_error
    raise "an error"
  end
end

class MyController < ActionController::Base
  def show
    render MyBrokenComponent.new
  end
end

Expected behavior

I expected to see the rails error page.

Actual behavior

A blank page.

A few things worth noting

1. If just one of the components raises an error, only that component will be blank. The rest of the page will work:

<!-- my_page_component.html.erb -->
<%= render SpanComponent.new("one") %>
<%= render MyBrokenComponent.new %>
<%= render SpanComponent.new("two") %>

The page will render:

<span>one</span>
<span>two</span>

2. If MyBrokenComponent raises during in the initializer, the page will be blank.

<!-- my_page_component.html.erb -->
<%= render SpanComponent.new("one") %>
<%= render MyBrokenComponent.new %>
<%= render SpanComponent.new("two") %>

3. If the component rendered by the controller raises an error in the initializer, the expected error page will be displayed.

class MyBrokenComponent < ViewComponent::Base
  erb_template <<-ERB
    foo bar
  ERB

  def initialize
    raise "an error"
  end
end

class MyController < ActionController::Base
  def show
    # the rails error page will be rendered
    render MyBrokenComponent.new 
  end
end

So all of that, makes me believe that the error suppressing is happening during the rendering phase.

Backtrace:

System configuration

Rails version: Rails 7.0.8
Ruby version: ruby 3.0.6p216 (2023-03-30 revision 23a532679b) [x86_64-darwin21]
Gem version: view_component (3.10.0), view_component (3.5.0), view_component (3.0.0) (without the erb_template syntax.

[reeganviljoen]

@mjacobus if you are able to add failing tests in a pr it would help a lot, otherwise someone will be able to do it

[mjacobus]

Update:

I downgraded view_component to 2.80.0 and the error was still there. So I think it is something in our application 🤔

[mjacobus]

@reeganviljoen noted! 👍🏻 I will dig some more, and I come back to it.

[mjacobus]

I found the culprit. That is https://github.com/newrelic/newrelic-ruby-agent.

It overrides the render method:

https://github.com/newrelic/newrelic-ruby-agent/blob/2968b6ccda8f4e8220e0a666cd72f52add3e3acc/lib/new_relic/agent/instrumentation/view_component/prepend.rb#L9-L11

Then rescues exceptions, and don't raise again:

https://github.com/newrelic/newrelic-ruby-agent/blob/2968b6ccda8f4e8220e0a666cd72f52add3e3acc/lib/new_relic/agent/instrumentation/view_component/instrumentation.rb#L17-L21

[reeganviljoen]

@mjacobus i also use new relic + view_component I will issue a bug report if you haven't already

[mjacobus]

Thank you @reeganviljoen.

This is the PR that introduced this behavior: https://github.com/newrelic/newrelic-ruby-agent/pull/2367/files#r1463895980

[mjacobus]

Here's a PR that should fix the issue: newrelic/newrelic-ruby-agent#2410

[reeganviljoen]

@mjacobus what a legend, can't wait for them to fix it 🙏

[mjacobus]

For the record, we can disable view component instrumentation with the instrumentation.view_component option.

# config/newrelic.yml
common: &default_settings
  # [...]
  instrumentation.view_component: disabled

[kinduff]

@mjacobus You are a legend, thank you so much!