Check for valid Zigbee channel. https://github.com/Koenkk/zigbee2mqtt/issues/1077

lib/zigbee.js

@@ -8,6 +8,11 @@ const Queue = require('queue');
 const zclId = require('zcl-id');
 
 const advancedSettings = settings.get().advanced;
+
+if (advancedSettings.channel < 11 || advancedSettings.channel > 26) {
+    throw new Error(`'${advancedSettings.channel}' is an invalid channel, use a channel between 11 - 26.`);
+}
+
 const shepherdSettings = {
     net: {
         panId: advancedSettings.pan_id,