After saving the editor disapears and save button throw an error

[clarkwinkelmann]

While trying to replicate a (probably unrelated) issue with a given setup, I noticed an issue with this extension.

Here's the setup:

Flarum core 0.1.0-beta.7
PHP 7.1.7-1+ubuntu16.04.1+deb.sury.org+1
Loaded extensions: Core, date, libxml, openssl, pcre, zlib, filter, hash, pcntl, Reflection, SPL, session, standard, mysqlnd, PDO, xml, calendar, ctype, curl, dom, mbstring, fileinfo, ftp, gd, gettext, iconv, json, exif, mcrypt, mysqli, pdo_mysql, Phar, posix, readline, shmop, SimpleXML, soap, sockets, sysvmsg, sysvsem, sysvshm, tokenizer, wddx, xmlreader, xmlwriter, xsl, zip, mongodb, Zend OPcache, xdebug
EXT flarum-approval v0.1.0-beta.7
EXT flarum-bbcode v0.1.0-beta.5
EXT oe800-bbcode-alerts 0.1.6
EXT clarkwinkelmann-comicsans v0.1.0
EXT datitisev-dashboard v0.1.0-beta.5
EXT flarum-emoji v0.1.0-beta.6
EXT clarkwinkelmann-emojionearea v0.1.1
EXT flarum-english v0.1.0-beta.7
EXT flagrow-bazaar 0.2.2
EXT flagrow-byobu 0.1.0-beta.18
EXT flagrow-upload 0.4.13
EXT flagrow-user-directory 0.1.0
EXT flagrow-users-list 0.1.2
EXT flarum-flags v0.1.0-beta.7
EXT sijad-recaptcha 0.0.2
EXT oe800-gravatar 0.1.2
EXT flarum-likes v0.1.0-beta.6
EXT flarum-lock v0.1.0-beta.7
EXT flarum-markdown v0.1.0-beta.5
EXT ganuonglachanh-markdown-editor 0.9
EXT s9e-mediaembed 0.3.2
EXT flarum-mentions v0.1.0-beta.7
EXT sijad-pages 0.1.0-beta.3
EXT wiseclock-profile-image-crop 0.1.1
EXT xengine-signature 0.1.2
EXT sijad-spoiler-alert 0.1.0
EXT flarum-sticky v0.1.0-beta.7
EXT flarum-subscriptions v0.1.0-beta.6
EXT flarum-suspend v0.1.0-beta.7
EXT flarum-tags v0.1.0-beta.8
Base URL: http://localhost:8000
Installation path: /home/clark/Projects/gravure/flarum-debug/flarum

Loading the signature page as normal:

After clicking save the editor disappears and only the signature content is left:

If I click the button at this time I get the following error:

Backtrace:

POST http://localhost:8000/api/settings/signature/validate

{
  "errors": [
    {
      "code": 500,
      "title": "Internal server error",
      "detail": "InvalidArgumentException: Expecting a DOMNodeList or DOMNode instance, an array, a string, or null, but got \"boolean\". in /home/clark/Projects/gravure/flarum-debug/flarum/vendor/symfony/dom-crawler/Crawler.php:123\nStack trace:\n#0 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/symfony/dom-crawler/Crawler.php(70): Symfony\\Component\\DomCrawler\\Crawler->add(false)\n#1 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/xengine/flarum-ext-signature/src/Validation/ValidateSignature.php(32): Symfony\\Component\\DomCrawler\\Crawler->__construct(false)\n#2 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/flarum/core/src/Http/Handler/ControllerRouteHandler.php(53): XEngine\\Signature\\Validation\\ValidateSignature->handle(Object(Zend\\Stratigility\\Http\\Request))\n#3 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/flarum/core/src/Http/Middleware/DispatchRoute.php(69): Flarum\\Http\\Handler\\ControllerRouteHandler->__invoke(Object(Zend\\Stratigility\\Http\\Request), Array)\n#4 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Dispatch.php(212): Flarum\\Http\\Middleware\\DispatchRoute->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\Next))\n#5 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Dispatch.php(88): Zend\\Stratigility\\Dispatch->dispatchCallableMiddleware(Object(Flarum\\Http\\Middleware\\DispatchRoute), Object(Zend\\Stratigility\\Next), Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), NULL)\n#6 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Next.php(160): Zend\\Stratigility\\Dispatch->__invoke(Object(Zend\\Stratigility\\Route), NULL, Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\Next))\n#7 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/flarum/core/src/Http/Middleware/SetLocale.php(51): Zend\\Stratigility\\Next->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response))\n#8 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Dispatch.php(212): Flarum\\Http\\Middleware\\SetLocale->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\Next))\n#9 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Dispatch.php(88): Zend\\Stratigility\\Dispatch->dispatchCallableMiddleware(Object(Flarum\\Http\\Middleware\\SetLocale), Object(Zend\\Stratigility\\Next), Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), NULL)\n#10 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Next.php(160): Zend\\Stratigility\\Dispatch->__invoke(Object(Zend\\Stratigility\\Route), NULL, Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\Next))\n#11 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/flarum/core/src/Http/Middleware/AuthenticateWithHeader.php(58): Zend\\Stratigility\\Next->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response))\n#12 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Dispatch.php(212): Flarum\\Http\\Middleware\\AuthenticateWithHeader->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\Next))\n#13 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Dispatch.php(88): Zend\\Stratigility\\Dispatch->dispatchCallableMiddleware(Object(Flarum\\Http\\Middleware\\AuthenticateWithHeader), Object(Zend\\Stratigility\\Next), Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), NULL)\n#14 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Next.php(160): Zend\\Stratigility\\Dispatch->__invoke(Object(Zend\\Stratigility\\Route), NULL, Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\Next))\n#15 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/flarum/core/src/Http/Middleware/AuthenticateWithSession.php(36): Zend\\Stratigility\\Next->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response))\n#16 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Dispatch.php(212): Flarum\\Http\\Middleware\\AuthenticateWithSession->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\Next))\n#17 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Dispatch.php(88): Zend\\Stratigility\\Dispatch->dispatchCallableMiddleware(Object(Flarum\\Http\\Middleware\\AuthenticateWithSession), Object(Zend\\Stratigility\\Next), Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), NULL)\n#18 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Next.php(160): Zend\\Stratigility\\Dispatch->__invoke(Object(Zend\\Stratigility\\Route), NULL, Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\Next))\n#19 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/flarum/core/src/Http/Middleware/RememberFromCookie.php(39): Zend\\Stratigility\\Next->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response))\n#20 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Dispatch.php(212): Flarum\\Http\\Middleware\\RememberFromCookie->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\Next))\n#21 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Dispatch.php(88): Zend\\Stratigility\\Dispatch->dispatchCallableMiddleware(Object(Flarum\\Http\\Middleware\\RememberFromCookie), Object(Zend\\Stratigility\\Next), Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), NULL)\n#22 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Next.php(160): Zend\\Stratigility\\Dispatch->__invoke(Object(Zend\\Stratigility\\Route), NULL, Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\Next))\n#23 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/flarum/core/src/Http/Middleware/StartSession.php(48): Zend\\Stratigility\\Next->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response))\n#24 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Dispatch.php(212): Flarum\\Http\\Middleware\\StartSession->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\Next))\n#25 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Dispatch.php(88): Zend\\Stratigility\\Dispatch->dispatchCallableMiddleware(Object(Flarum\\Http\\Middleware\\StartSession), Object(Zend\\Stratigility\\Next), Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), NULL)\n#26 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Next.php(160): Zend\\Stratigility\\Dispatch->__invoke(Object(Zend\\Stratigility\\Route), NULL, Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\Next))\n#27 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/flarum/core/src/Api/Middleware/FakeHttpMethods.php(33): Zend\\Stratigility\\Next->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response))\n#28 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Dispatch.php(212): Flarum\\Api\\Middleware\\FakeHttpMethods->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\Next))\n#29 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Dispatch.php(88): Zend\\Stratigility\\Dispatch->dispatchCallableMiddleware(Object(Flarum\\Api\\Middleware\\FakeHttpMethods), Object(Zend\\Stratigility\\Next), Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), NULL)\n#30 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Next.php(160): Zend\\Stratigility\\Dispatch->__invoke(Object(Zend\\Stratigility\\Route), NULL, Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\Next))\n#31 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/flarum/core/src/Http/Middleware/ParseJsonBody.php(31): Zend\\Stratigility\\Next->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response))\n#32 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Dispatch.php(212): Flarum\\Http\\Middleware\\ParseJsonBody->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\Next))\n#33 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Dispatch.php(88): Zend\\Stratigility\\Dispatch->dispatchCallableMiddleware(Object(Flarum\\Http\\Middleware\\ParseJsonBody), Object(Zend\\Stratigility\\Next), Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), NULL)\n#34 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Next.php(160): Zend\\Stratigility\\Dispatch->__invoke(Object(Zend\\Stratigility\\Route), NULL, Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\Next))\n#35 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/flarum/core/src/Api/Middleware/HandleErrors.php(45): Zend\\Stratigility\\Next->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response))\n#36 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Dispatch.php(212): Flarum\\Api\\Middleware\\HandleErrors->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\Next))\n#37 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Dispatch.php(88): Zend\\Stratigility\\Dispatch->dispatchCallableMiddleware(Object(Flarum\\Api\\Middleware\\HandleErrors), Object(Zend\\Stratigility\\Next), Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), NULL)\n#38 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/Next.php(160): Zend\\Stratigility\\Dispatch->__invoke(Object(Zend\\Stratigility\\Route), NULL, Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\Next))\n#39 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-stratigility/src/MiddlewarePipe.php(111): Zend\\Stratigility\\Next->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response))\n#40 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/flarum/core/src/Http/AbstractServer.php(55): Zend\\Stratigility\\MiddlewarePipe->__invoke(Object(Zend\\Stratigility\\Http\\Request), Object(Zend\\Stratigility\\Http\\Response), Object(Zend\\Stratigility\\NoopFinalHandler))\n#41 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/zendframework/zend-diactoros/src/Server.php(166): Flarum\\Http\\AbstractServer->__invoke(Object(Zend\\Diactoros\\ServerRequest), Object(Zend\\Diactoros\\Response), Object(Zend\\Stratigility\\NoopFinalHandler))\n#42 /home/clark/Projects/gravure/flarum-debug/flarum/vendor/flarum/core/src/Http/AbstractServer.php(36): Zend\\Diactoros\\Server->listen(Object(Zend\\Stratigility\\NoopFinalHandler))\n#43 /home/clark/Projects/gravure/flarum-debug/flarum/api.php(16): Flarum\\Http\\AbstractServer->listen()\n#44 /home/clark/Projects/gravure/flarum-debug/flarum/server.php(14): require('/home/clark/Pro...')\n#45 {main}"
    }
  ]
}