Merge pull request #15153 from calixteman/1778692

[Annotation] A push button can have no action (bug 1778692)

src/display/annotation_layer.js

@@ -1440,8 +1440,8 @@ class PushButtonWidgetAnnotationElement extends LinkAnnotationElement {
       container.title = this.data.alternativeText;
     }
 
-    if (this.enableScripting && this.hasJSActions) {
-      const linkElement = container.lastChild;
+    const linkElement = container.lastChild;
+    if (this.enableScripting && this.hasJSActions && linkElement) {
       this._setDefaultPropertiesFromJS(linkElement);
 
       linkElement.addEventListener("updatefromsandbox", jsEvent => {

test/pdfs/bug1778692.pdf.link

@@ -0,0 +1,2 @@
+https://bugzilla.mozilla.org/attachment.cgi?id=9284681
+

test/test_manifest.json

@@ -6837,5 +6837,15 @@
          "rotation": 270
        }
      }
+   },
+   { "id": "bug1778692",
+   "file": "pdfs/bug1778692.pdf",
+   "md5": "8855414caaa04fbbdfad1545d1c8a8ae",
+   "rounds": 1,
+   "link": true,
+   "firstPage": 2,
+   "lastPage": 2,
+   "type": "eq",
+   "annotations": true
    }
 ]