getFileKindLabel() / TypeError: must be of the type string, null returned.

[ddbr]

Description

When adding dxf and dwg using extraAllowedFileExtensions following error occurs when uploading a dxf file within admin Console -> Assets:

'extraAllowedFileExtensions' => 'dxf, dwg'

Error log:

> 2018-01-25 09:41:24 [213.196.159.4][1][-][error][TypeError] TypeError: Return value of craft\helpers\Assets::getFileKindLabel() must be of the type string, null returned in /var/www/html/vendor/craftcms/cms/src/helpers/Assets.php:288
Stack trace:
#0 /var/www/html/vendor/craftcms/cms/src/elements/Asset.php(893): craft\helpers\Assets::getFileKindLabel('unknown')
#1 /var/www/html/vendor/craftcms/cms/src/base/Element.php(1640): craft\elements\Asset->tableAttributeHtml('kind')
#2 /var/www/html/vendor/twig/twig/lib/Twig/Extension/Core.php(1595): craft\base\Element->getTableAttributeHtml('kind')
#3 /var/www/html/vendor/craftcms/cms/src/helpers/Template.php(76): twig_get_attribute(Object(craft\web\twig\Environment), Object(Twig_Source), Object(craft\elements\Asset), 'getTableAttribu...', Array, 'method', false, false)
#4 /var/www/html/storage/runtime/compiled_templates/6d/6d626ae811629fd3271e0c97435556f2ef0d5048763e97af2ea83627b442c0c6.php(138): craft\helpers\Template::attribute(Object(craft\web\twig\Environment), Object(Twig_Source), Object(craft\elements\Asset), 'getTableAttribu...', Array, 'method')
#5 /var/www/html/vendor/twig/twig/lib/Twig/Template.php(389): __TwigTemplate_7e74f9bdbb76ea693d036ffae11164eda40d130043fdd24dc3590b53ec839633->doDisplay(Array, Array)
#6 /var/www/html/vendor/craftcms/cms/src/web/twig/Template.php(51): Twig_Template->displayWithErrorHandling(Array, Array)
#7 /var/www/html/vendor/twig/twig/lib/Twig/Template.php(366): craft\web\twig\Template->displayWithErrorHandling(Array, Array)
#8 /var/www/html/vendor/craftcms/cms/src/web/twig/Template.php(32): Twig_Template->display(Array, Array)
#9 /var/www/html/storage/runtime/compiled_templates/ac/ac18635758b5c277dd17ae309ba5c86b9790f843cfcb4567db08956b97d17a11.php(77): craft\web\twig\Template->display(Array)
#10 /var/www/html/vendor/twig/twig/lib/Twig/Template.php(389): __TwigTemplate_0373910080618291bb3a21c0cd52e7420ece5fa4e0566e5cd3e4dfa02fbe9978->doDisplay(Array, Array)
#11 /var/www/html/vendor/craftcms/cms/src/web/twig/Template.php(51): Twig_Template->displayWithErrorHandling(Array, Array)
#12 /var/www/html/vendor/twig/twig/lib/Twig/Template.php(366): craft\web\twig\Template->displayWithErrorHandling(Array, Array)
#13 /var/www/html/vendor/craftcms/cms/src/web/twig/Template.php(32): Twig_Template->display(Array, Array)
#14 /var/www/html/vendor/twig/twig/lib/Twig/Template.php(374): craft\web\twig\Template->display(Array)
#15 /var/www/html/vendor/twig/twig/lib/Twig/Environment.php(289): Twig_Template->render(Array)
#16 /var/www/html/vendor/craftcms/cms/src/web/View.php(292): Twig_Environment->render('_elements/table...', Array)
#17 /var/www/html/vendor/craftcms/cms/src/base/Element.php(441): craft\web\View->renderTemplate('_elements/table...', Array)
#18 /var/www/html/vendor/craftcms/cms/src/controllers/ElementIndexesController.php(391): craft\base\Element::indexHtml(Object(craft\elements\db\AssetQuery), Array, Array, 'folder:4/folder...', 'index', true, true)
#19 /var/www/html/vendor/craftcms/cms/src/controllers/ElementIndexesController.php(119): craft\controllers\ElementIndexesController->_elementResponseData(true, true)
#20 [internal function]: craft\controllers\ElementIndexesController->actionGetElements()
#21 /var/www/html/vendor/yiisoft/yii2/base/InlineAction.php(57): call_user_func_array(Array, Array)
#22 /var/www/html/vendor/yiisoft/yii2/base/Controller.php(157): yii\base\InlineAction->runWithParams(Array)
#23 /var/www/html/vendor/craftcms/cms/src/web/Controller.php(80): yii\base\Controller->runAction('get-elements', Array)
#24 /var/www/html/vendor/yiisoft/yii2/base/Module.php(528): craft\web\Controller->runAction('get-elements', Array)
#25 /var/www/html/vendor/craftcms/cms/src/web/Application.php(243): yii\base\Module->runAction('element-indexes...', Array)
#26 /var/www/html/vendor/craftcms/cms/src/web/Application.php(421): craft\web\Application->runAction('element-indexes...', Array)
#27 /var/www/html/vendor/craftcms/cms/src/web/Application.php(203): craft\web\Application->_processActionRequest(Object(craft\web\Request))
#28 /var/www/html/vendor/yiisoft/yii2/base/Application.php(386): craft\web\Application->handleRequest(Object(craft\web\Request))
#29 /var/www/html/web/index.php(23): yii\base\Application->run()
#30 {main}

Steps to reproduce

1. Add 'extraAllowedFileExtensions' => 'dxf, dwg' in /config/General.php
2. Upload dxf File within Assets in Admin Console
3. Show folder where File had beeing upladed.

Temp Fix

When adjusting Function getFileKindLabel() to return '' instead of null, the error does not occur.

cms/src/helpers/Assets.php

Line 302 in 6d5ebfe

return null;

Additional info

• Craft version: Craft Pro 3.0.0-RC5
• PHP version: 7.0.22-0ubuntu0.17.04.1
• Database driver & version: MySQL 5.7.20-0ubuntu0.17.04.1
• Plugins & versions: Redactor 1.0.0.1 / XML Sitemap v1.0.5