feat: streamlined role-revocation logic

src/BusProNet/Model/CrmAttributesResponse.php

@@ -87,12 +87,13 @@ class CrmAttributesResponse
     {
         $crmSelections = [];
 
-        foreach ($this->getAttributeGroups() as $group) {
+        // a response the CRM sent no attributes in still has to flatten to an empty set
+        foreach ($this->getAttributeGroups() ?? [] as $group) {
             /** @var CrmAttributeGroup $group */
             if (false === isset($crmSelections[$group->getLabel()])) {
                 $crmSelections[$group->getLabel()] = [];
             }
-            foreach ($group->getAttributes() as $attribute) {
+            foreach ($group->getAttributes() ?? [] as $attribute) {
                 /** @var CrmAttribute $attribute */
                 if (false === $attribute->isSelected()) {
                     continue;