diff --git a/src/core/document.js b/src/core/document.js
index b1e1caaec..7324c9980 100644
--- a/src/core/document.js
+++ b/src/core/document.js
@@ -707,10 +707,18 @@ class Page {
     // Ensure that the structTree will contain the page's annotations.
     await this._parsedAnnotations;
 
-    const structTree = await this.pdfManager.ensure(this, "_parseStructTree", [
-      structTreeRoot,
-    ]);
-    return this.pdfManager.ensure(structTree, "serializable");
+    try {
+      const structTree = await this.pdfManager.ensure(
+        this,
+        "_parseStructTree",
+        [structTreeRoot]
+      );
+      const data = await this.pdfManager.ensure(structTree, "serializable");
+      return data;
+    } catch (ex) {
+      warn(`getStructTree: "${ex}".`);
+      return null;
+    }
   }
 
   /**
diff --git a/src/core/struct_tree.js b/src/core/struct_tree.js
index a8766e92e..59ba40cb6 100644
--- a/src/core/struct_tree.js
+++ b/src/core/struct_tree.js
@@ -757,7 +757,10 @@ class StructTreePage {
 
     const parent = dict.get("P");
 
-    if (!parent || isName(parent.get("Type"), "StructTreeRoot")) {
+    if (
+      !(parent instanceof Dict) ||
+      isName(parent.get("Type"), "StructTreeRoot")
+    ) {
       if (!this.addTopLevelNode(dict, element)) {
         map.delete(dict);
       }