Make sure "roundcube/roundcubemail" install path is always available

src/ExtensionInstaller.php

@@ -2,6 +2,7 @@
 
 namespace Roundcube\Composer;
 
+use Composer\Installer\InstallationManager;
 use Composer\Installer\LibraryInstaller;
 use Composer\Package\PackageInterface;
 use Composer\Package\Version\VersionParser;
@@ -43,15 +44,26 @@ protected function setRoundcubemailInstallPath(InstalledRepositoryInterface $ins
 
     protected function getRoundcubemailInstallPath(): string
     {
+        // install path is not set at composer download phase
+        // never assume any path, but for this known composer behaviour get it from backtrace instead
+        if ($this->roundcubemailInstallPath === null) {
+            $backtrace = debug_backtrace();
+            foreach ($backtrace as $frame) {
+                // relies on https://github.com/composer/composer/blob/2.7.4/src/Composer/Installer/InstallationManager.php#L243
+                if (($frame['object'] ?? null) instanceof InstallationManager
+                    && ($frame['function'] ?? null) === 'downloadAndExecuteBatch'
+                ) {
+                    $this->setRoundcubemailInstallPath($frame['args'][0]);
+                }
+            }
+        }
+
         return $this->roundcubemailInstallPath;
     }
 
     public function getInstallPath(PackageInterface $package)
     {
-        if (
-            !$this->supports($package->getType())
-            || $this->roundcubemailInstallPath === null // install path is not known at download phase
-        ) {
+        if (!$this->supports($package->getType())) {
             return parent::getInstallPath($package);
         }