Locale from session can be a symbol, but causes sidekiq web to error out

[mishaelajay]

Ruby version: 3.2.4
Rails version: 7.1.3
Sidekiq / Pro / Enterprise version(s): 7.2.4

Please include your initializer, sidekiq.yml, and any error message with the full backtrace.

I have a middleware setup on my application which will set the I18n.locale based on either the URL parameter
'locale', or if not available, use the first of the HTTP_ACCEPT_LANGUAGE
values to infer the locale to be used. It sets said locale as a symbol.

Sidekiq web throws the following error now on opening: TypeError: no implicit conversion of nil into Hash

On digging further this was thrown from here:

sidekiq/lib/sidekiq/web/helpers.rb

Line 19 in 30786e0

global.merge!(strs[lang])

@strings[lang] ||= settings.locales.each_with_object({}) do |path, global|
    find_locale_files(lang).each do |file|
    strs = YAML.safe_load(File.read(file))
    global.merge!(strs[lang])
end

Since this was working until Sidekiq 7.2.2 i figured this must be due to a recent change which led me to:
https://github.com/sidekiq/sidekiq/pull/6217/files#diff-a19b19d20df90597eaac2e2edc433b5d56d1d30a8501029bfd9688a8980dd150R124-R127

# session[:locale] is set via the locale selector from the footer
# defined?(session) && session are used to avoid exceptions when running tests
return session[:locale] if defined?(session) && session&.[](:locale)

Prior to this change, when the :locale is not set within the session it defaults to "en"
Post this change, it uses the session['locale'] if available which in my application is always a symbol.
But since the strings method has strs which loads the locales as a hash with strings as keys it will cause the above mentioned error.

I have a possible fix for this in this PR: #6272