Fix: unable to add accounts without plain set up (#1769)

* Update family.rb

Fix for: https://github.com/maybe-finance/maybe/issues/1766

Signed-off-by: Jacco Broeren <jaccobroeren@freedom.nl>

* Update family.rb

Add commenting.

Signed-off-by: Jacco Broeren <jaccobroeren@freedom.nl>

---------

Signed-off-by: Jacco Broeren <jaccobroeren@freedom.nl>

app/models/family.rb

@@ -63,6 +63,9 @@ class Family < ApplicationRecord
       self.class.plaid_us_provider
     end
 
+    # early return when no provider
+    return nil unless provider
+
     provider.get_link_token(
       user_id: id,
       webhooks_url: webhooks_url,