Fix: Check for _graphic._src before displaying menu image (fixes #142)

README.md

@@ -160,6 +160,6 @@ No known limitations.
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 <a href="https://community.adaptlearning.org/" target="_blank"><img src="https://github.com/adaptlearning/documentation/blob/master/04_wiki_assets/plug-ins/images/adapt-logo-mrgn-lft.jpg" alt="adapt learning logo" align="right"></a><br>
 **Author / maintainer:** Adapt Core Team with [contributors](https://github.com/adaptlearning/adapt-contrib-boxmenu/graphs/contributors)<br>
-**Accessibility support:** WAI AA <br>
+**Accessibility support:** WAI AA<br>
 **RTL support:** Yes<br>
 **Cross-platform coverage:** Chrome, Chrome for Android, Firefox (ESR + latest version), Edge, IE11, Safari 14 for macOS/iOS/iPadOS, Opera<br>