Lark: Uncaught exception:

Michelf\Markdown::defaultTransform(): Argument #1 ($text) must be of type string, null given, called in /www/webvol32/lq/53odwblzfe1rglf/rikardkarlsson.se/src/textfilter/filter/CTextFilter.php on line 148

#0 /www/webvol32/lq/53odwblzfe1rglf/rikardkarlsson.se/src/textfilter/filter/CTextFilter.php(148): Michelf\Markdown::defaultTransform(NULL)
#1 /www/webvol32/lq/53odwblzfe1rglf/rikardkarlsson.se/src/textfilter/filter/CTextFilter.php(73): CTextFilter::markdown(NULL)
#2 /www/webvol32/lq/53odwblzfe1rglf/rikardkarlsson.se/src/textfilter/filter/CTextFilter.php(57): CTextFilter::applyFilterFunction(NULL, 'markdown')
#3 /www/webvol32/lq/53odwblzfe1rglf/rikardkarlsson.se/src/app/page/CWebPage.php(102): CTextFilter::doFilter(NULL, 'markdown')
#4 /www/webvol32/lq/53odwblzfe1rglf/rikardkarlsson.se/public_html/fysik/uppgifter.php(22): CWebPage->getPageHtml('0020-impuls-9-2...')
#5 {main}