Too much data passed as arguments to js_call_amd("block_accessibility_filescan/init", "init")

[devnoot]

Appears when Moodle debug messages is set to developer

Too much data passed as arguments to js_call_amd("block_accessibility_filescan/init", "init"). Generally there are better ways to pass lots of data from PHP to JavaScript, for example via Ajax, data attributes, ... . This warning is triggered if the argument string becomes longer than 1024 characters.
line 1070 of /lib/outputrequirementslib.php: call to debugging()
line 289 of /blocks/accessibility_filescan/block_accessibility_filescan.php: call to page_requirements_manager->js_call_amd()
line 337 of /blocks/moodleblock.class.php: call to block_accessibility_filescan->get_content()
line 231 of /blocks/moodleblock.class.php: call to block_base->formatted_contents()
line 1231 of /lib/blocklib.php: call to block_base->get_content_for_output()
line 1289 of /lib/blocklib.php: call to block_manager->create_block_contents()
line 377 of /lib/blocklib.php: call to block_manager->ensure_content_created()
line 4237 of /lib/outputrenderers.php: call to block_manager->region_has_content()
line 50 of /theme/boost/layout/drawers.php: call to core_renderer->blocks()
line 1483 of /lib/outputrenderers.php: call to include()
line 1408 of /lib/outputrenderers.php: call to core_renderer->render_page_layout()
line 307 of /course/view.php: call to core_renderer->header()

[sbozzini]

Based on my tests, it seems that the warning appears when there are more than 3 PDFs in the course (not so unusual).