Show warning if user already set an application password

Signed-off-by: DL6ER <dl6er@dl6er.de>

scripts/pi-hole/js/settings-api.js

@@ -266,6 +266,8 @@ function processWebServerConfig() {
   })
     .done(function (data) {
       setConfigValues("webserver", "webserver", data.config.webserver);
+      if (data.config.webserver.api.app_pwhash.value.length > 0)
+        $("#existing_apppw_warning").show();
     })
     .fail(function (data) {
       apiFailure(data);

settings-api.lp

@@ -260,6 +260,9 @@ mg.include('scripts/pi-hole/lua/settings_header.lp','r')
                 <p>IMPORTANT: The app password generated here will only be shown
                 once and cannot be recovered. Make sure to store it in a safe
                 place!</p>
+                <div class="danger-area" style="display: none;" id="existing_apppw_warning">
+                    <h4>Application password already configured</h4>Enabling the new app password will forcefully log out all existing applications.
+                </div>
             </div>
             <div class="modal-footer">
                 <button type="button" id="apppw_clear" class="btn btn-default btn-danger pull-left">Remove currently set app password</button>