diff -up ./src/Resolver/AutoResolver.php.php8 ./src/Resolver/AutoResolver.php
--- ./src/Resolver/AutoResolver.php.php8	2021-03-31 11:23:21.738880158 +0200
+++ ./src/Resolver/AutoResolver.php	2021-03-31 11:23:24.532869778 +0200
@@ -54,7 +54,7 @@ class AutoResolver extends Resolver
         }
 
         // use an explicit auto-resolution?
-        $rtype = $rparam->getClass();
+        $rtype = @$rparam->getClass();
         if ($rtype && isset($this->types[$rtype->name])) {
             return $this->types[$rtype->name];
         }
diff -up ./src/Resolver/Resolver.php.php8 ./src/Resolver/Resolver.php
--- ./src/Resolver/Resolver.php.php8	2021-03-31 11:21:49.964221101 +0200
+++ ./src/Resolver/Resolver.php	2021-03-31 11:22:01.635177740 +0200
@@ -266,7 +266,7 @@ class Resolver
         $spec = [[], []];
 
         // fetch the values for parents so we can inherit them
-        $parent = get_parent_class($class);
+        $parent = class_exists($class) ? get_parent_class($class) : null;
         if ($parent) {
             $spec = $this->getUnified($parent);
         }