Issue with behat test when initialising the block

[laurentdavid]

Running another behat test that is intialising the block leads to an exception.

BeforeStep # behat_hooks::before_step()
Exception: Other backtraces found:
line 216 of /blocks/rss_thumbnails/block_rss_thumbnails.php: call to behat_error_handler()
line 89 of /blocks/rss_thumbnails/block_rss_thumbnails.php: call to block_rss_thumbnails->config_is_valid()
line 341 of /blocks/moodleblock.class.php: call to block_rss_thumbnails->get_content()
line 235 of /blocks/moodleblock.class.php: call to block_base->formatted_contents()
line 1181 of /lib/blocklib.php: call to block_base->get_content_for_output()
line 1239 of /lib/blocklib.php: call to block_manager->create_block_contents()
line 374 of /lib/blocklib.php: call to block_manager->ensure_content_created()
line 3965 of /lib/outputrenderers.php: call to block_manager->region_has_content()
line 149 of /theme/clboost/classes/local/utils.php: call to core_renderer->blocks()
line 28 of /theme/clboost/layout/frontpage.php: call to theme_clboost()
line 1376 of /lib/outputrenderers.php: call to include()
line 1306 of /lib/outputrenderers.php: call to core_renderer->render_page_layout()