Missing string?

[dasistwas]

/cache/admin.php gives that message in debug mode:

String does not exist. Please check your string definition for cachedef_schistory/local_shopping_cart

    line 10640 of /lib/moodlelib.php: call to debugging()
    line 623 of /cache/classes/definition.php: call to lang_string->__construct()
    line 205 of /cache/classes/administration_helper.php: call to cache_definition->get_name()
    line 89 of /admin/tool/forcedcache/classes/cache_administration_helper.php: call to core_cache\administration_helper::get_definition_summaries()
    line 83 of /cache/admin.php: call to tool_forcedcache_cache_administration_helper->generate_admin_page()

[dasistwas]

Another one:

Invalid get_string() identifier: 'cachedef_schistory' or component 'local_shopping_cart'. Perhaps you are missing $string['cachedef_schistory'] = ''; in /var/www/moodleroot/local/shopping_cart/lang/en/local_shopping_cart.php?

    line 356 of /lib/classes/string_manager_standard.php: call to debugging()
    line 10669 of /lib/moodlelib.php: call to core_string_manager_standard->get_string()
    line 10703 of /lib/moodlelib.php: call to lang_string->get_string()
    line ? of unknownfile: call to lang_string->__toString()
    line 212 of /lib/classes/collator.php: call to Collator->asort()
    line 322 of /lib/classes/collator.php: call to core_collator::asort()
    line 237 of /cache/classes/output/renderer.php: call to core_collator::asort_array_of_arrays_by_key()
    line 94 of /admin/tool/forcedcache/classes/cache_administration_helper.php: call to core_cache\output\renderer->definition_summaries()
    line 83 of /cache/admin.php: call to tool_forcedcache_cache_administration_helper->generate_admin_page()