Anonymous Checkout issues, no order email or no order user

why not simply setting the radios as required in function commerce_login_step_form_commerce_checkout_form_alter() like so
...
'#options' => array(
'anonymous' => t('Continue without login'),
'login' => t('Login with an existing account'),
),
'#required' => TRUE,
...

We've been using this module and see the same problem. However, I'd like to propose to fix it by using the existing "Continue" button, instead of disabling it. I think this is a cleaner approach. Let me know what you think!

I am finding in my site I am able to have an anonymous order with an existing email. Nothing seems to prevent this from happening. Is there even a quick rule I could put in?

To clarify:

1. Legacy/Existing user does an anonymous checkout
2. Said user enters in email and clicks continue
3. No check occurs to say USER EXISTS already

The suggestion from #2 is good and works wonderful! Please add this as a quickfix release!

The patch from #3 changes several things so that we should have a deeper look.

Is there still an active maintainer for this module willing to fix the bugs? I'd like to offer my help in maintainership if you're no more active.

PS: If we'd like to disable the process button, the Drupal form #states API will help, I think!

This does not prevent a user from skipping the selection of "Choose how you want to checkout"

This addresses item #1 in summary, which other patch only concerned #2. Looks like we should be solid on fix now for original issue summary.

+++ b/commerce_login_step.module
@@ -34,6 +34,11 @@ function commerce_login_step_form_commerce_checkout_form_alter(&$form, &$form_st
+    $existing_form_suffix = $form['#prefix'];

#prefix is used in both lines, and it raises notices, if $form['#prefix'] is not defined.

+++ b/commerce_login_step.module
@@ -135,4 +145,4 @@ function commerce_login_step_checkout_form_submit($form, &$form_state) {
\ No newline at end of file

I needed to remove this code-style improvement, to apply another patch (2362777-9)

Added an improved version of patch #7

Those patches went horribly wrong :( Re-Uploaded them.