Exception in ERB template does not render exception view properly

[jasonkim]

We've noticed that any error within the ERB template does not handle the error the same way as the error coming from controller. After some debugging, I noticed that there's an error thrown within create_template call. From there, I found this PR that touched the relevant section. And validated the behavior with modified test below.

Steps to reproduce

I've changed the test scenario here to wrap the error case with noop if-statement, which should not change the behavior.
It changes the file actionview/test/fixtures/test/runtime_error.html.erb to

<h1>Oh no!</h1>
This template has a runtime error
<% if true %>
  <%= method_that_does_not_exist %>
<% end %>
Yikes!

This is used by the test actionview/test/template/render_test.rb

Your reproduction script goes here

After making the above change (or checkout this fork), run

cd actionview
bin/test test/template/render_test.rb

Expected behavior

The test should pass

Actual behavior

Test fails with error

Error:
LazyViewRenderTest#test_render_runtime_error:
RuntimeError: 
    /workspaces/rails/actionview/lib/action_view/template/handlers/erb.rb:113:in `find_offset'
    /workspaces/rails/actionview/lib/action_view/template/handlers/erb.rb:44:in `translate_location'
    /workspaces/rails/actionview/lib/action_view/template.rb:182:in `translate_location'
    /workspaces/rails/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb:238:in `spot'
    /workspaces/rails/actionview/test/template/render_test.rb:220:in `test_render_runtime_error'


bin/test test/template/render_test.rb:212

System configuration

Rails version:
main

Ruby version:
3.2

[casperisfine]

cc @tenderlove.

I'm not very familiar with this code, but the parser very clearly give up by raising RuntimeError when it fails to parse the template somehow.

Such raw raise suggest that it was expected this case wouldn't be hit, but clearly it is.

I suspect there are two fixes needed here:

• This code is clearly valid, so we should be able to parse it fine, something in the parser need to be improved.
• Even if we fixed that particular error, we should raise a proper error when we fail to parse, so that we can fallback to not mapping the source code.

I'll have a quick look at the second part of the fix.

[obie]

Brief comment to say that I'm seeing this constantly on my 7.1 apps and it's a huge PITA.