If you didn't configure LLDP and try to show neighbors, this will result in an error.
sever@vyos-1.3:~$ show lldp neighbors
Traceback (most recent call last):
File "/usr/libexec/vyos/op_mode/lldp_op.py", line 145, in <module>
neighbors = minidom.parseString(_get_neighbors())
File "/usr/lib/python3.7/xml/dom/minidom.py", line 1968, in parseString
return expatbuilder.parseString(string)
File "/usr/lib/python3.7/xml/dom/expatbuilder.py", line 925, in parseString
return builder.parseString(string)
File "/usr/lib/python3.7/xml/dom/expatbuilder.py", line 223, in parseString
parser.Parse(string, True)
xml.parsers.expat.ExpatError: syntax error: line 1, column 0