The dynamic text plugin is many years out of date. It was created as
a way of allowing text to be changeable before Gimp's text tool
supported that. For the past ten years or so the plugin has been
completely useless and therefore hasn't been maintained. I'm not sure
whether that explains the errors you see, but whether it does or not
you are wasting your time: this plugin doesn't do anything more than
Gimp's text tool already does much better.
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