Icon is broken in EM #20
Description
When installing this extension in a website deployed with helhum/typo3-secure-web, only assets available are those found in Resources/Public. This means that EXT:<extension>/ext_icon.[gif|png] is not accessible.
According to \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::getExtensionIcon you should just move and rename your extension icon:
/ext_icon.gif -> /Resources/Public/Icons/Extension.gif
works with many of my extensions. This works since at least TYPO3 v8 and is compatible with TER detail page.