after passing the previous error also and goin to admin panel - configurations i get this error
TypeError: Return value of Dfe\YandexKassa\Source\Option::Dfe\YandexKassa\Source\{closure}() must be of the type string, null returned in /home/lelasinfo/public_html/vendor/mage2pro/yandex-kassa/Source/Option.php:37 Stack trace: #0 [internal function]: Dfe\YandexKassa\Source\Option->Dfe\YandexKassa\Source\{closure}(Array) mage2pro/yandex-kassa#1 /home/lelasinfo/public_html/vendor/mage2pro/core/Core/lib/array/map.php(97): array_map(Object(Closure), Array) mage2pro/yandex-kassa#2 /home/lelasinfo/public_html/vendor/mage2pro/yandex-kassa/Source/Option.php(40): df_map(Object(Closure), Array) mage2pro/yandex-kassa#3 /home/lelasinfo/public_html/vendor/mage2pro/core/Config/Source.php(126): Dfe\YandexKassa\Source\Option->map() mage2pro/yandex-kassa#4 /home/lelasinfo/public_html/vendor/magento/module-config/Model/Config/Structure/Element/Field.php(461): Df\Config\Source->toOptionArray(false) mage2pro/core#226 /home/lelasinfo/public_html/vendor/magento/module-config/Model/Config/Structure/Element/Field.php(379): Magento\Config\Model\Config\Structure\Element\Field->_getOptionsFromSourceModel(Object(Dfe\YandexKassa\Source\Option)) #6 /home/lelasinfo/public_html/vendor/magento/module-config/Block/System/Config/Form.php(394): Magento\Config\Model\Config\Structure\Element\Field->getOptions() #7 /home/lelasinfo/public_html/vendor/magento/module-config/Block/System/Config/Form.php(316): Magento\Config\Block\System\Config\Form->_initElement(Object(Magento\Config\Model\Config\Structure\Element\Field\Interceptor), Object(Magento\Framework\Data\Form\Element\Fieldset\Interceptor), 'df_payment/yand...', '', '') #8 /home/lelasinfo/public_html/vendor/magento/module-config/Block/System/Config/Form.php(256): Magento\Config\Block\System\Config\Form->initFields(Object(Magento\Framework\Data\Form\Element\Fieldset\Interceptor), Object(Magento\Config\Model\Config\Structure\Element\Group), Object(Magento\Config\Model\Config\Structure\Element\Section)) #9 /home/lelasinfo/public_html/vendor/magento/module-config/Block/System/Config/Form.php(202): Magento\Config\Block\System\Config\Form->_initGroup(Object(Magento\Config\Model\Config\Structure\Element\Group), Object(Magento\Config\Model\Config\Structure\Element\Section), Object(Magento\Framework\Data\Form)) #10 /home/lelasinfo/public_html/vendor/magento/module-config/Block/System/Config/Form.php(542): Magento\Config\Block\System\Config\Form->initForm() #11 /home/lelasinfo/public_html/vendor/magento/framework/View/Element/AbstractBlock.php(1110): Magento\Config\Block\System\Config\Form->_beforeToHtml() #12 /home/lelasinfo/public_html/vendor/magento/framework/View/Element/AbstractBlock.php(1115): Magento\Framework\View\Element\AbstractBlock->Magento\Framework\View\Element\{closure}() #13 /home/lelasinfo/public_html/vendor/magento/framework/View/Element/AbstractBlock.php(675): Magento\Framework\View\Element\AbstractBlock->_loadCache() #14 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(578): Magento\Framework\View\Element\AbstractBlock->toHtml() #15 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(555): Magento\Framework\View\Layout->_renderBlock('system\\config\\f...') #16 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(510): Magento\Framework\View\Layout->renderNonCachedElement('system\\config\\f...') #17 /home/lelasinfo/public_html/vendor/magento/framework/View/Element/AbstractBlock.php(522): Magento\Framework\View\Layout->renderElement('system\\config\\f...', true) #18 /home/lelasinfo/public_html/vendor/magento/module-config/view/adminhtml/templates/system/config/edit.phtml(32): Magento\Framework\View\Element\AbstractBlock->getChildHtml('form') #19 /home/lelasinfo/public_html/vendor/magento/framework/View/TemplateEngine/Php.php(71): include('/home/lelasinfo...') #20 /home/lelasinfo/public_html/vendor/magento/framework/Interception/Interceptor.php(58): Magento\Framework\View\TemplateEngine\Php->render(Object(Magento\Config\Block\System\Config\Edit\Interceptor), '/home/lelasinfo...', Array) #21 /home/lelasinfo/public_html/vendor/magento/framework/Interception/Interceptor.php(138): Magento\Framework\View\TemplateEngine\Php\Interceptor->___callParent('render', Array) #22 /home/lelasinfo/public_html/vendor/magento/framework/Interception/Interceptor.php(153): Magento\Framework\View\TemplateEngine\Php\Interceptor->Magento\Framework\Interception\{closure}(Object(Magento\Config\Block\System\Config\Edit\Interceptor), '/home/lelasinfo...', Array) #23 /home/lelasinfo/public_html/generated/code/Magento/Framework/View/TemplateEngine/Php/Interceptor.php(23): Magento\Framework\View\TemplateEngine\Php\Interceptor->___callPlugins('render', Array, Array) #24 /home/lelasinfo/public_html/vendor/magento/framework/View/Element/Template.php(273): Magento\Framework\View\TemplateEngine\Php\Interceptor->render(Object(Magento\Config\Block\System\Config\Edit\Interceptor), '/home/lelasinfo...', Array) #25 /home/lelasinfo/public_html/vendor/magento/framework/View/Element/Template.php(303): Magento\Framework\View\Element\Template->fetchView('/home/lelasinfo...') #26 /home/lelasinfo/public_html/vendor/magento/module-backend/Block/Template.php(141): Magento\Framework\View\Element\Template->_toHtml() #27 /home/lelasinfo/public_html/vendor/magento/framework/View/Element/AbstractBlock.php(1111): Magento\Backend\Block\Template->_toHtml() #28 /home/lelasinfo/public_html/vendor/magento/framework/View/Element/AbstractBlock.php(1115): Magento\Framework\View\Element\AbstractBlock->Magento\Framework\View\Element\{closure}() #29 /home/lelasinfo/public_html/vendor/magento/framework/View/Element/AbstractBlock.php(675): Magento\Framework\View\Element\AbstractBlock->_loadCache() #30 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(578): Magento\Framework\View\Element\AbstractBlock->toHtml() #31 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(555): Magento\Framework\View\Layout->_renderBlock('system.config.e...') #32 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(510): Magento\Framework\View\Layout->renderNonCachedElement('system.config.e...') #33 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(606): Magento\Framework\View\Layout->renderElement('system.config.e...', false) #34 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(557): Magento\Framework\View\Layout->_renderContainer('content', false) #35 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(510): Magento\Framework\View\Layout->renderNonCachedElement('content') #36 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(606): Magento\Framework\View\Layout->renderElement('content', false) #37 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(557): Magento\Framework\View\Layout->_renderContainer('admin.scope.col...', false) #38 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(510): Magento\Framework\View\Layout->renderNonCachedElement('admin.scope.col...') #39 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(606): Magento\Framework\View\Layout->renderElement('admin.scope.col...', false) #40 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(557): Magento\Framework\View\Layout->_renderContainer('main.col', false) #41 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(510): Magento\Framework\View\Layout->renderNonCachedElement('main.col') #42 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(606): Magento\Framework\View\Layout->renderElement('main.col', false) #43 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(557): Magento\Framework\View\Layout->_renderContainer('page.main.conta...', false) #44 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(510): Magento\Framework\View\Layout->renderNonCachedElement('page.main.conta...') #45 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(606): Magento\Framework\View\Layout->renderElement('page.main.conta...', false) #46 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(557): Magento\Framework\View\Layout->_renderContainer('page.content', false) #47 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(510): Magento\Framework\View\Layout->renderNonCachedElement('page.content') #48 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(606): Magento\Framework\View\Layout->renderElement('page.content', false) #49 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(557): Magento\Framework\View\Layout->_renderContainer('page.wrapper', false) #50 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(510): Magento\Framework\View\Layout->renderNonCachedElement('page.wrapper') #51 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(606): Magento\Framework\View\Layout->renderElement('page.wrapper', false) #52 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(557): Magento\Framework\View\Layout->_renderContainer('backend.page', false) #53 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(510): Magento\Framework\View\Layout->renderNonCachedElement('backend.page') #54 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(606): Magento\Framework\View\Layout->renderElement('backend.page', false) #55 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(557): Magento\Framework\View\Layout->_renderContainer('root', false) #56 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(510): Magento\Framework\View\Layout->renderNonCachedElement('root') #57 /home/lelasinfo/public_html/vendor/magento/framework/View/Layout.php(975): Magento\Framework\View\Layout->renderElement('root') #58 /home/lelasinfo/public_html/generated/code/Magento/Framework/View/Layout/Interceptor.php(41): Magento\Framework\View\Layout->getOutput() #59 /home/lelasinfo/public_html/vendor/magento/framework/View/Result/Page.php(258): Magento\Framework\View\Layout\Interceptor->getOutput() #60 /home/lelasinfo/public_html/vendor/magento/framework/View/Result/Layout.php(171): Magento\Framework\View\Result\Page->render(Object(Magento\Framework\App\Response\Http\Interceptor)) #61 /home/lelasinfo/public_html/generated/code/Magento/Backend/Model/View/Result/Page/Interceptor.php(32): Magento\Framework\View\Result\Layout->renderResult(Object(Magento\Framework\App\Response\Http\Interceptor)) #62 /home/lelasinfo/public_html/vendor/magento/framework/App/Http.php(120): Magento\Backend\Model\View\Result\Page\Interceptor->renderResult(Object(Magento\Framework\App\Response\Http\Interceptor)) #63 /home/lelasinfo/public_html/vendor/magento/framework/Interception/Interceptor.php(58): Magento\Framework\App\Http->launch() #64 /home/lelasinfo/public_html/vendor/magento/framework/Interception/Interceptor.php(138): Magento\Framework\App\Http\Interceptor->___callParent('launch', Array) #65 /home/lelasinfo/public_html/vendor/mage2pro/core/Framework/Plugin/App/Http.php(10): Magento\Framework\App\Http\Interceptor->Magento\Framework\Interception\{closure}() #66 /home/lelasinfo/public_html/vendor/magento/framework/Interception/Interceptor.php(135): Df\Framework\Plugin\App\Http->aroundLaunch(Object(Magento\Framework\App\Http\Interceptor), Object(Closure)) #67 /home/lelasinfo/public_html/vendor/magento/framework/Interception/Interceptor.php(153): Magento\Framework\App\Http\Interceptor->Magento\Framework\Interception\{closure}() #68 /home/lelasinfo/public_html/generated/code/Magento/Framework/App/Http/Interceptor.php(23): Magento\Framework\App\Http\Interceptor->___callPlugins('launch', Array, NULL) #69 /home/lelasinfo/public_html/vendor/magento/framework/App/Bootstrap.php(263): Magento\Framework\App\Http\Interceptor->launch() #70 /home/lelasinfo/public_html/pub/index.php(29): Magento\Framework\App\Bootstrap->run(Object(Magento\Framework\App\Http\Interceptor)) #71 {main}
Originally posted by @AlaaL in mage2pro/core#226 (comment)