I don't know what a minimal example for this would be, but you can get the error if you take an empty wiki, and import both the tiddler SVGImage1 and the plugin from the demo, set the default tiddler to SVGImage1 and then reload the wiki. From what I can tell the tiddler is rendered before the script is loaded. I don't know how to make sure that the script is loaded before the widget does anything.
-- You received this message because you are subscribed to the Google Groups "TiddlyWiki" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/tiddlywiki. To view this discussion on the web visit https://groups.google.com/d/msgid/tiddlywiki/1dac1de4-30ba-44e2-88d4-8f90c68f3871%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.

