Sounds like a duplicate of #989, #1016, #1056, #1262, #1847, geany/geany-plugins#432, geany/geany-plugins#442, geany/geany-plugins#446, [130](https://sourceforge.net/p/geany-plugins/bugs/130/), etc.
A good way to report bugs for Geany is to first disable all plugins, if the issue persists, then you know to post the issue here, if it stops, then you know the issue is meant for the Geany-Plugins project. The next thing that's useful is to search existing issues for your error message to see if it's already been reported and/or fixed. Examples:
For Geany: https://github.com/geany/geany/issues?utf8=%E2%9C%93&q=sci_get_contents_...
For Geany-Plugins: https://github.com/geany/geany-plugins/issues?utf8=%E2%9C%93&q=sci_get_c...