fix: handle blank email from GitHub OAuth

- Validate email is present before attempting to find or create a Member
- Show friendly error message when GitHub returns blank/missing email
- Prevents ActiveRecord::RecordInvalid error with multiple validation errors

Author: mroderick

app/controllers/auth_services_controller.rb

@@ -26,8 +26,15 @@ def create
 
       finish_registration || redirect_to(referer_or_dashboard_path)
     else
-        member = Member.find_by(email: omnihash[:info][:email])
-        member ||= Member.new(email: omnihash[:info][:email])
+        email = omnihash[:info][:email].to_s.strip
+
+        if email.blank?
+          flash[:error] = I18n.t('notifications.email_missing_from_provider')
+          return redirect_to root_url
+        end
+
+        member = Member.find_by(email:)
+        member ||= Member.new(email:)
 
         member.name    ||= omnihash[:info][:name]&.split(' ')&.first || ''
         member.surname ||= omnihash[:info][:name]&.split(' ')&.drop(1)&.join(' ') || ''

config/locales/en.yml

@@ -201,6 +201,7 @@ en:
     not_logged_in: "You must be logged in to access this page."
     signing_up: "Thanks for signing up. Please fill in your details to complete the registration process."
     authentication_error: "Authentication failed. Please try again."
+    email_missing_from_provider: "We could not retrieve your email address from GitHub. Please make sure your GitHub account has a public email address and try again."
   navigation:
     dashboard: "Dashboard"
     code_of_conduct: "Code of Conduct"