show port error disable state in device ports view

lib/App/Netdisco/DB/Result/DevicePort.pm

@@ -175,8 +175,7 @@ device port.
 
 __PACKAGE__->might_have( properties => 'App::Netdisco::DB::Result::DevicePortProperties', {
   'foreign.ip' => 'self.ip', 'foreign.port' => 'self.port',
-  }, { join_type => 'LEFT OUTER' }
-);
+});
 
 =head2 ssid
 
@@ -308,6 +307,15 @@ ID assigned to untagged frames received on the port).
 
 sub native { return (shift)->vlan }
 
+=head2 error_disable_cause
+
+Returns the textual reason given by the device if the port is in an error
+state, or else `undef` if the port is not in an error state.
+
+=cut
+
+sub error_disable_cause { return (shift)->get_column('properties_error_disable_cause') }
+
 =head2 vlan_count
 
 Returns the number of VLANs active on this device port. Enable this column by

lib/App/Netdisco/DB/ResultSet/DevicePort.pm

@@ -104,6 +104,32 @@ sub only_free_ports {
     );
 }
 
+=head2 with_properties
+
+This is a modifier for any C<search()> which
+will add the following additional synthesized columns to the result set:
+
+=over 4
+
+=item error_disable_cause
+
+=back
+
+=cut
+
+sub with_properties {
+  my ($rs, $cond, $attrs) = @_;
+
+  return $rs
+    ->search_rs($cond, $attrs)
+    ->search({},
+      {
+        '+select' => ['properties.error_disable_cause'],
+        '+as' => ['properties_error_disable_cause'],
+        join => 'properties',
+      });
+}
+
 =head2 with_vlan_count
 
 This is a modifier for any C<search()> (including the helpers below) which