fix Name must start with a leading slash

Refs #312

.gitattributes

@@ -1 +1,2 @@
-*.pdf binary
+*.pdf binary
+*.pdf diff

CHANGELOG.md

@@ -5,6 +5,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+- Fixed `Name must start with a leading slash` when adding an external document to a `pdfjs` document, and adding that result to another `pdfjs` document again (caused by a `null` object reference due to object streams). Also fixes duplicate objects when adding external documents with
+pages in object streams.
 
 ## [2.5.2]
 ### Fixed

lib/external.js

@@ -48,16 +48,19 @@ module.exports = class ExternalDocument {
     const kids = this.pages.get("Kids");
     const filter = page ? (i) => i === page - 1 : undefined;
 
+    // As a first iteration, simply register all page objects to ensure they exist for inter-page
+    // references (as they are not part of the `addObjectsRecursive` in the second iteration)
+    for (const page of this._iterPagesRecursively(doc, kids, filter)) {
+      doc._registerObject(page, true);
+    }
+
     for (const page of this._iterPagesRecursively(doc, kids, filter)) {
       // if the page object does not define its MediaBox, explicitly set its MediaBox to the
       // value defined by its parent Pages object
       if (!page.properties.has("MediaBox") && this.mediaBox) {
         page.properties.set("MediaBox", this.mediaBox);
       }
 
-      // add single page
-      doc._registerObject(page, true);
-
       // first, register objects to assign IDs (for references)
       const objects = [];
       Parser.addObjectsRecursive(objects, page, 0);

lib/object/reference.js

@@ -21,6 +21,9 @@ class PDFReference {
   }
 
   toString() {
+    if (this.object.id === null) {
+      throw new TypeError("Tried to write reference with `null` object id");
+    }
     return this.object.id + " " + this.object.rev + " R";
   }
 

lib/parser/parser.js

@@ -68,6 +68,13 @@ class Parser {
         if (objects.indexOf(value.object) > -1) {
           break;
         }
+
+        // skip references to other pages
+        const type = value.object.properties.get("Type");
+        if (type && type.toString() === "/Page") {
+          break;
+        }
+
         objects.push(value.object);
         Parser.addObjectsRecursive(objects, value.object);
         break;