S complains about writability too much

[zerocrates]

When trying to edit a page, if the files directory is not writable, an exception is raised:

exception 'Omeka\File\Exception\RuntimeException' with message 'Base path "/mnt/storage/htdocs/omeka3/files" is not a writable directory.' in /mnt/storage/htdocs/omeka3/application/src/File/Store/LocalStore.php:35
Stack trace:
#0 /mnt/storage/htdocs/omeka3/application/src/Service/LocalStoreFactory.php(27): Omeka\File\Store\LocalStore->__construct('/mnt/storage/ht...', 'http://zerocrat...')
#1 [internal function]: Omeka\Service\LocalStoreFactory->createService(Object(Zend\ServiceManager\ServiceManager), 'omekafilelocals...', 'Omeka\\File\\Loca...')
#2 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-servicemanager/src/ServiceManager.php(939): call_user_func(Array, Object(Zend\ServiceManager\ServiceManager), 'omekafilelocals...', 'Omeka\\File\\Loca...')
#3 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-servicemanager/src/ServiceManager.php(1097): Zend\ServiceManager\ServiceManager->createServiceViaCallback(Array, 'omekafilelocals...', 'Omeka\\File\\Loca...')
#4 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-servicemanager/src/ServiceManager.php(638): Zend\ServiceManager\ServiceManager->createFromFactory('omekafilelocals...', 'Omeka\\File\\Loca...')
#5 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-servicemanager/src/ServiceManager.php(598): Zend\ServiceManager\ServiceManager->doCreate('Omeka\\File\\Loca...', 'omekafilelocals...')
#6 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-servicemanager/src/ServiceManager.php(530): Zend\ServiceManager\ServiceManager->create(Array)
#7 /mnt/storage/htdocs/omeka3/application/src/File/Manager.php(40): Zend\ServiceManager\ServiceManager->get('Omeka\\File\\Loca...')
#8 /mnt/storage/htdocs/omeka3/application/src/File/Manager.php(192): Omeka\File\Manager->getStore()
#9 /mnt/storage/htdocs/omeka3/application/src/Api/Representation/MediaRepresentation.php(74): Omeka\File\Manager->getThumbnailUrl('square', Object(DoctrineProxies\__CG__\Omeka\Entity\Media))
#10 /mnt/storage/htdocs/omeka3/application/view-shared/common/attachments-form.phtml(41): Omeka\Api\Representation\MediaRepresentation->thumbnailUrl('square')
#11 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-view/src/Renderer/PhpRenderer.php(501): include('/mnt/storage/ht...')
#12 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-view/src/Helper/Partial.php(61): Zend\View\Renderer\PhpRenderer->render('common/attachme...', Array)
#13 [internal function]: Zend\View\Helper\Partial->__invoke('common/attachme...', Array)
#14 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-view/src/Renderer/PhpRenderer.php(393): call_user_func_array(Object(Zend\View\Helper\Partial), Array)
#15 /mnt/storage/htdocs/omeka3/application/src/Site/BlockLayout/AbstractBlockLayout.php(46): Zend\View\Renderer\PhpRenderer->__call('partial', Array)
#16 /mnt/storage/htdocs/omeka3/application/src/Site/BlockLayout/AbstractBlockLayout.php(46): Zend\View\Renderer\PhpRenderer->partial('common/attachme...', Array)
#17 /mnt/storage/htdocs/omeka3/application/src/Site/BlockLayout/ItemList.php(20): Omeka\Site\BlockLayout\AbstractBlockLayout->attachmentsForm(Object(Zend\View\Renderer\PhpRenderer), Object(Omeka\Api\Representation\SiteRepresentation), Object(Omeka\Api\Representation\SitePageBlockRepresentation))
#18 /mnt/storage/htdocs/omeka3/application/src/View/Helper/BlockLayout.php(95): Omeka\Site\BlockLayout\ItemList->form(Object(Zend\View\Renderer\PhpRenderer), Object(Omeka\Api\Representation\SiteRepresentation), Object(Omeka\Api\Representation\SitePageBlockRepresentation))
#19 /mnt/storage/htdocs/omeka3/application/src/View/Helper/BlockLayout.php(60): Omeka\View\Helper\BlockLayout->form(Object(Omeka\Api\Representation\SitePageBlockRepresentation))
#20 /mnt/storage/htdocs/omeka3/application/view-admin/omeka/site-admin/page/edit.phtml(21): Omeka\View\Helper\BlockLayout->forms(Object(Omeka\Api\Representation\SitePageRepresentation))
#21 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-view/src/Renderer/PhpRenderer.php(501): include('/mnt/storage/ht...')
#22 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-view/src/View.php(205): Zend\View\Renderer\PhpRenderer->render(Object(Zend\View\Model\ViewModel))
#23 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-view/src/View.php(233): Zend\View\View->render(Object(Zend\View\Model\ViewModel))
#24 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-view/src/View.php(198): Zend\View\View->renderChildren(Object(Zend\View\Model\ViewModel))
#25 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-mvc/src/View/Http/DefaultRenderingStrategy.php(103): Zend\View\View->render(Object(Zend\View\Model\ViewModel))
#26 [internal function]: Zend\Mvc\View\Http\DefaultRenderingStrategy->render(Object(Zend\Mvc\MvcEvent))
#27 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-eventmanager/src/EventManager.php(444): call_user_func(Array, Object(Zend\Mvc\MvcEvent))
#28 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-eventmanager/src/EventManager.php(205): Zend\EventManager\EventManager->triggerListeners('render', Object(Zend\Mvc\MvcEvent), Array)
#29 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-mvc/src/Application.php(353): Zend\EventManager\EventManager->trigger('render', Object(Zend\Mvc\MvcEvent))
#30 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-mvc/src/Application.php(328): Zend\Mvc\Application->completeRequest(Object(Zend\Mvc\MvcEvent))
#31 /mnt/storage/htdocs/omeka3/index.php(17): Zend\Mvc\Application->run()
#32 {main}

Next exception 'Zend\ServiceManager\Exception\ServiceNotCreatedException' with message 'An exception was raised while creating "Omeka\File\LocalStore"; no instance returned' in /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-servicemanager/src/ServiceManager.php:946
Stack trace:
#0 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-servicemanager/src/ServiceManager.php(1097): Zend\ServiceManager\ServiceManager->createServiceViaCallback(Array, 'omekafilelocals...', 'Omeka\\File\\Loca...')
#1 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-servicemanager/src/ServiceManager.php(638): Zend\ServiceManager\ServiceManager->createFromFactory('omekafilelocals...', 'Omeka\\File\\Loca...')
#2 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-servicemanager/src/ServiceManager.php(598): Zend\ServiceManager\ServiceManager->doCreate('Omeka\\File\\Loca...', 'omekafilelocals...')
#3 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-servicemanager/src/ServiceManager.php(530): Zend\ServiceManager\ServiceManager->create(Array)
#4 /mnt/storage/htdocs/omeka3/application/src/File/Manager.php(40): Zend\ServiceManager\ServiceManager->get('Omeka\\File\\Loca...')
#5 /mnt/storage/htdocs/omeka3/application/src/File/Manager.php(192): Omeka\File\Manager->getStore()
#6 /mnt/storage/htdocs/omeka3/application/src/Api/Representation/MediaRepresentation.php(74): Omeka\File\Manager->getThumbnailUrl('square', Object(DoctrineProxies\__CG__\Omeka\Entity\Media))
#7 /mnt/storage/htdocs/omeka3/application/view-shared/common/attachments-form.phtml(41): Omeka\Api\Representation\MediaRepresentation->thumbnailUrl('square')
#8 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-view/src/Renderer/PhpRenderer.php(501): include('/mnt/storage/ht...')
#9 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-view/src/Helper/Partial.php(61): Zend\View\Renderer\PhpRenderer->render('common/attachme...', Array)
#10 [internal function]: Zend\View\Helper\Partial->__invoke('common/attachme...', Array)
#11 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-view/src/Renderer/PhpRenderer.php(393): call_user_func_array(Object(Zend\View\Helper\Partial), Array)
#12 /mnt/storage/htdocs/omeka3/application/src/Site/BlockLayout/AbstractBlockLayout.php(46): Zend\View\Renderer\PhpRenderer->__call('partial', Array)
#13 /mnt/storage/htdocs/omeka3/application/src/Site/BlockLayout/AbstractBlockLayout.php(46): Zend\View\Renderer\PhpRenderer->partial('common/attachme...', Array)
#14 /mnt/storage/htdocs/omeka3/application/src/Site/BlockLayout/ItemList.php(20): Omeka\Site\BlockLayout\AbstractBlockLayout->attachmentsForm(Object(Zend\View\Renderer\PhpRenderer), Object(Omeka\Api\Representation\SiteRepresentation), Object(Omeka\Api\Representation\SitePageBlockRepresentation))
#15 /mnt/storage/htdocs/omeka3/application/src/View/Helper/BlockLayout.php(95): Omeka\Site\BlockLayout\ItemList->form(Object(Zend\View\Renderer\PhpRenderer), Object(Omeka\Api\Representation\SiteRepresentation), Object(Omeka\Api\Representation\SitePageBlockRepresentation))
#16 /mnt/storage/htdocs/omeka3/application/src/View/Helper/BlockLayout.php(60): Omeka\View\Helper\BlockLayout->form(Object(Omeka\Api\Representation\SitePageBlockRepresentation))
#17 /mnt/storage/htdocs/omeka3/application/view-admin/omeka/site-admin/page/edit.phtml(21): Omeka\View\Helper\BlockLayout->forms(Object(Omeka\Api\Representation\SitePageRepresentation))
#18 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-view/src/Renderer/PhpRenderer.php(501): include('/mnt/storage/ht...')
#19 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-view/src/View.php(205): Zend\View\Renderer\PhpRenderer->render(Object(Zend\View\Model\ViewModel))
#20 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-view/src/View.php(233): Zend\View\View->render(Object(Zend\View\Model\ViewModel))
#21 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-view/src/View.php(198): Zend\View\View->renderChildren(Object(Zend\View\Model\ViewModel))
#22 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-mvc/src/View/Http/DefaultRenderingStrategy.php(103): Zend\View\View->render(Object(Zend\View\Model\ViewModel))
#23 [internal function]: Zend\Mvc\View\Http\DefaultRenderingStrategy->render(Object(Zend\Mvc\MvcEvent))
#24 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-eventmanager/src/EventManager.php(444): call_user_func(Array, Object(Zend\Mvc\MvcEvent))
#25 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-eventmanager/src/EventManager.php(205): Zend\EventManager\EventManager->triggerListeners('render', Object(Zend\Mvc\MvcEvent), Array)
#26 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-mvc/src/Application.php(353): Zend\EventManager\EventManager->trigger('render', Object(Zend\Mvc\MvcEvent))
#27 /mnt/storage/htdocs/omeka3/vendor/zendframework/zend-mvc/src/Application.php(328): Zend\Mvc\Application->completeRequest(Object(Zend\Mvc\MvcEvent))
#28 /mnt/storage/htdocs/omeka3/index.php(17): Zend\Mvc\Application->run()
#29 {main}

That kind of check should probably only happen if we're actually trying to write something there, or even only on install.