js: prevent js exception in pages without pill control

Add check to test if a pill control has been found and don't try
to add mac data to non existent client pill controls.

ogcp/static/js/ogcp.js

@@ -5,6 +5,11 @@ let updateTimeoutId = null;
 
 async function show_client_mac(pill_id) {
     const pill = $('#' +pill_id);
+
+    if (!pill.length) {
+        return
+    }
+
     const ip = pill.html().split('<br>')[1]
 
     if (!macs.get(ip)) {

ogcp/templates/base.html

@@ -111,7 +111,7 @@
     <!-- ChartJS -->
     <script src="{{ url_for('static', filename='AdminLTE/plugins/chart.js/Chart.min.js') }}"></script>
 
-    <script src="{{ url_for('static', filename='js/ogcp.js') }}?v=3"></script>
+    <script src="{{ url_for('static', filename='js/ogcp.js') }}?v=4"></script>
 
     <script>
         // error messages