Validate document nodes before use (#493)

* Validate document.body before use in loadScripts

This also fixes an issue where reject wasn't being passed to loadScriptSentinel.

* Validate document nodes before use in _getSiteColor

* Validate document.body before use in _getViewport

* Validate document.body before use in setContentScale

* Validate document.body before use in docImposterCreate

1 files changed, 4 insertions, 1 deletions

diff --git a/ext/fg/js/document.js b/ext/fg/js/document.js
index 3b4cc28f..6103c7c5 100644
--- a/ext/fg/js/document.js
+++ b/ext/fg/js/document.js
@@ -28,6 +28,9 @@ function docSetImposterStyle(style, propertyName, value) {
 }
 
 function docImposterCreate(element, isTextarea) {
+    const body = document.body;
+    if (body === null) { return [null, null]; }
+
     const elementStyle = window.getComputedStyle(element);
     const elementRect = element.getBoundingClientRect();
     const documentRect = document.documentElement.getBoundingClientRect();
@@ -78,7 +81,7 @@ function docImposterCreate(element, isTextarea) {
     }
 
     container.appendChild(imposter);
-    document.body.appendChild(container);
+    body.appendChild(container);
 
     // Adjust size
     const imposterRect = imposter.getBoundingClientRect();