Fixes #30529 nxos_facts ipv6 interface (#31286)

Signed-off-by: Trishna Guha <trishnaguha17@gmail.com>

lib/ansible/modules/network/nxos/nxos_facts.py

@@ -348,7 +348,9 @@ class Interfaces(FactsBase):
         return objects
 
     def parse_ipv6_interfaces(self, data):
+        try:
             data = data['TABLE_intf']
+            if data:
                 if isinstance(data, dict):
                     data = [data]
                 for item in data:
@@ -356,6 +358,10 @@ class Interfaces(FactsBase):
                     intf = self.facts['interfaces'][name]
                     intf['ipv6'] = self.transform_dict(item, self.INTERFACE_IPV6_MAP)
                     self.facts['all_ipv6_addresses'].append(item['ROW_intf']['addr'])
+            else:
+                return ""
+        except TypeError:
+            return ""
 
 
 class Legacy(FactsBase):