removing and adding of preshared_keys fixed

_modules/wireguard.py

         s = '%s private-key %s' % (s, filename)
     if peer:
         s = '%s peer %s' % (s, peer)
-    if preshared_key:
+    if preshared_key != None:
         if not peer:
             return 'If preshared_key is given, peer must also be given'
         fd2, filename2 = mkstemp(text=True)

_states/wireguard.py

                  allowed_ips=None, preshared_key=None):
     ret = dict(name=name, changes=dict(), result=False, comment=None)
 
-    show = __salt__['wg.show'](interface)
+    show = __salt__['wg.show'](interface, hide_keys=False)
     if not show:
         ret['comment'] = 'Interface %s does not exist.' % (interface)
         return ret
 
-    show = __salt__['wg.show'](name=interface, peer=name)
+    show = __salt__['wg.show'](name=interface, peer=name, hide_keys=False)
     if not show:
         __salt__['wg.set'](interface, peer=name, endpoint=endpoint,
                 persistent_keepalive=persistent_keepalive,
     if sorted(show.get('allowed ips')) != sorted(allowed_ips):
         __salt__['wg.set'](interface, peer=name, allowed_ips=','.join(allowed_ips))
         ret['changes']['allowed ips'] = dict(new=allowed_ips, old=show.get('allowed ips'))
-    if show.get('preshared key') and preshared_key and show.get('preshared key') != preshared_key:
+    print(show.get('preshared key'), preshared_key)
+    if preshared_key and show.get('preshared key') != preshared_key:
         __salt__['wg.set'](interface, peer=name, preshared_key=preshared_key)
         ret['changes']['preshared key'] = 'preshared key changed.'
-    if show.get('preshared key') and not preshared_key:
+    elif show.get('preshared key') and not preshared_key:
         __salt__['wg.set'](interface, peer=name, preshared_key='')
         ret['changes']['preshared key'] = 'preshared key deleted.'