Don't crash on unknown 'migration' directories

Fixes this error:

PHP Fatal error:  Call to a member function getName() on a non-object in
/datastore/DEVEL/framework/Core/lib/Horde/Core/Db/Migration.php on line 91

Signed-off-by: Jan Schneider <jan@horde.org>
Bug: 13013

framework/Core/lib/Horde/Core/Db/Migration.php

@@ -87,8 +87,14 @@ public function __construct($basedir = null, $pearconf = null)
         // Loop through installed PEAR packages.
         $registry = $pear->getRegistry();
         foreach (glob($pear->get('data_dir') . '/*/migration') as $dir) {
-            $app = $registry->getPackage(
-                basename(dirname($dir)), 'pear.horde.org')->getName();
+            $package = $registry->getPackage(
+                basename(dirname($dir)), 'pear.horde.org');
+            if ($package == false) {
+                Horde::log("Ignoring package in directory $dir", Horde_Log::WARN);
+                continue;
+            }
+
+            $app = $package->getName();
             if (!in_array($app, $this->apps)) {
                 $this->apps[] = $app;
                 $this->_lower[] = Horde_String::lower($app);