fix a coredump for api 'lyd_parse_xml' when action has no namespace

[fredgan]

Hi,Michal,
there is a coredump in api lyd_parse_xml when action has no namespace in XML data, and I try to fix it, please review it , thanks.

my sample yang module, XML data and test it with yanglint (the latest version 1.8.7) are as follows:
the yang module,mod.yang :

module mod {
    prefix abc;
    namespace "urn:cesnet:mod";

    yang-version 1.1;

    container action {
        action act {
            input {
                leaf l {
                    type string;
                }
            }

            output {
                leaf l2 {
                    type string;
                }
            }
        }
    }
}

the XML data,data.xml:

<action>
  <act>
    <l>test</l>
  </act>
</action>

using yanglint with the command (yanglint -t rpc -f xml mod.yang data.xml) , the result appears a coredump

root@oss-0007:/home/sample_test# yanglint -v
yanglint SO 1.8.7
root@oss-0007:/home/sample_test# yanglint -t rpc -f xml mod.yang data.xml
Segmentation fault (core dumped)
root@oss-0007:/home/sample_test#

[michalvasko]

Hi Fred,
right, seems like a simple fix and the correct one. Thanks, merging.

Regards,
Michal