Scan forward until text tokens match

Text tokens may be conditionally appended to the output buffer.  For
example if we have a template like this:

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

In the above case, a string literal (`"    "`) will be conditionally
appended to the output buffer with some code like below:

```ruby
@output_buffer.safe_append='    '.freeze
```

This commit teaches text tokens (string literals) to scan forward in the
compiled template until it finds the literal, thereby skipping the code
generated for appending to the output buffer.

Related to:

* Bug: #48173
* PR: #48184

actionview/lib/action_view/template/handlers/erb.rb

@@ -114,15 +114,23 @@ def find_offset(compiled, source_tokens, error_column)
             tok_name, str = *tok
             case tok_name
             when :TEXT
+              loop do
+                break if compiled.match?(str)
+                compiled.getch
+              end
               raise LocationParsingError unless compiled.scan(str)
             when :CODE
-              raise LocationParsingError, "We went too far" if compiled.pos > error_column
+              if compiled.pos > error_column
+                raise LocationParsingError, "We went too far"
+              end
 
               if compiled.pos + str.bytesize >= error_column
                 offset = error_column - compiled.pos
                 return passed_tokens.map(&:last).join.bytesize + offset
               else
-                raise LocationParsingError unless compiled.scan(str)
+                unless compiled.scan(str)
+                  raise LocationParsingError, "Couldn't find code snippet"
+                end
               end
             when :OPEN
               next_tok = source_tokens.first.last

actionview/test/template/render_test.rb

@@ -222,7 +222,7 @@ def test_render_runtime_error
       assert_equal 6, translated_spot[:first_column]
     end
 
-    def test_render_location_map_failure
+    def test_render_location_conditional_append
       ex = assert_raises(ActionView::Template::Error) {
         @view.render(template: "test/unparseable_runtime_error")
       }
@@ -232,7 +232,7 @@ def test_render_location_map_failure
       translating_frame = ActionDispatch::ExceptionWrapper::SourceMapLocation.new(erb_btl, ex.template)
       translated_spot = translating_frame.spot(ex.cause)
 
-      assert_not_nil translated_spot[:first_column]
+      assert_equal 8, translated_spot[:first_column]
     end
   end