Safer checks for apidoc renderer

extensions/apidoc/renderers/BaseRenderer.php

@@ -71,7 +71,7 @@ abstract class BaseRenderer extends Component
         $links = [];
         foreach ($types as $type) {
             $postfix = '';
-            if (!is_object($type)) {
+            if (is_string($type)) {
                 if (substr_compare($type, '[]', -2, 2) === 0) {
                     $postfix = '[]';
                     $type = substr($type, 0, -2);
@@ -85,7 +85,7 @@ abstract class BaseRenderer extends Component
                     ltrim($type, '\\');
                 }
             }
-            if (!is_object($type)) {
+            if (is_string($type)) {
                 $linkText = ltrim($type, '\\');
                 if ($title !== null) {
                     $linkText = $title;
@@ -110,7 +110,7 @@ abstract class BaseRenderer extends Component
                 } else {
                     $links[] = $type;
                 }
-            } else {
+            } elseif ($type instanceof BaseDoc) {
                 $linkText = $type->name;
                 if ($title !== null) {
                     $linkText = $title;