[{reqId}] {exception_url}   PHP Warning: mb_substr() expects parameter 2 to be integer, float given

from /srv/mediawiki/php-1.37.0-wmf.20/extensions/Scribunto/includes/engines/LuaCommon/UstringLibrary.php(319)
#0 [internal function]: MWExceptionHandler::handleError(integer, string, string, integer, array)
#1 /srv/mediawiki/php-1.37.0-wmf.20/extensions/Scribunto/includes/engines/LuaCommon/UstringLibrary.php(319): mb_substr(string, double, double, string)
#2 /srv/mediawiki/php-1.37.0-wmf.20/extensions/Scribunto/includes/engines/LuaSandbox/LuaSandboxCallback.php(26): Scribunto_LuaUstringLibrary->ustringSub(string, double, double)
#3 [internal function]: Scribunto_LuaSandboxCallback->__call(string, array)
#4 /srv/mediawiki/php-1.37.0-wmf.20/extensions/Scribunto/includes/engines/LuaSandbox/LuaSandboxInterpreter.php(113): LuaSandboxFunction->call(LuaSandboxFunction, LuaSandboxFunction)
#5 /srv/mediawiki/php-1.37.0-wmf.20/extensions/Scribunto/includes/engines/LuaCommon/LuaEngine.php(445): Scribunto_LuaSandboxInterpreter->callFunction(LuaSandboxFunction, LuaSandboxFunction, LuaSandboxFunction)
#6 /srv/mediawiki/php-1.37.0-wmf.20/extensions/Scribunto/includes/common/ApiScribuntoConsole.php(102): Scribunto_LuaEngine->runConsole(array)
#7 /srv/mediawiki/php-1.37.0-wmf.20/extensions/Scribunto/includes/common/ApiScribuntoConsole.php(68): ApiScribuntoConsole->runConsole(array)
#8 /srv/mediawiki/php-1.37.0-wmf.20/includes/api/ApiMain.php(1844): ApiScribuntoConsole->execute()
#9 /srv/mediawiki/php-1.37.0-wmf.20/includes/api/ApiMain.php(823): ApiMain->executeAction()
#10 /srv/mediawiki/php-1.37.0-wmf.20/includes/api/ApiMain.php(794): ApiMain->executeActionWithErrorHandling()
#11 /srv/mediawiki/php-1.37.0-wmf.20/api.php(90): ApiMain->execute()
#12 /srv/mediawiki/php-1.37.0-wmf.20/api.php(45): wfApiMain()
#13 /srv/mediawiki/w/api.php(3): require(string)
#14 {main}