▼テンプレート
[EC-CUBE] 2.17.2
[レンタルサーバ] localhost
[OS] MacOS 12.1
[PHP] PHP8.0
[データベース] MySQL 5.7.29
[WEBサーバ] Apache/2.4.46
[ブラウザ] safari 15.2
[現象]
PHP8.0で「お問い合わせ」画面で「お問い合わせ内容」を省略して、「確認ページへ」を押すとシステムエラーとなる。
PHP7.4ならこの現象は発生しない。

＜error.logの内容＞
2022/03/26 08:38:37 [/eccube-2/html/contact/index.php] Fatal error(E_ERROR): Uncaught TypeError: Cannot access offset of type string on string in /XXXXX/data/Smarty/templates_c/default/a6b601a572db0ab44c8ea6c4be47feb33ac4074d_0.file.index.tpl.php:186
Stack trace:
#0 /XXXXX/data/vendor/smarty/smarty/libs/sysplugins/smarty_template_resource_base.php(123): content_623d69b4085fe1_59811840(Object(Smarty_Internal_Template))
#1 /XXXXX/data/vendor/smarty/smarty/libs/sysplugins/smarty_template_compiled.php(114): Smarty_Template_Resource_Base->getRenderedTemplateCode(Object(Smarty_Internal_Template))
#2 /XXXXX/data/vendor/smarty/smarty/libs/sysplugins/smarty_internal_template.php(216): Smarty_Template_Compiled->render(Object(Smarty_Internal_Template))
#3 /XXXXX/data/vendor/smarty/smarty/libs/sysplugins/smarty_internal_template.php(385): Smarty_Internal_Template->render()
#4 /XXXXX/data/Smarty/templates_c/default/06128250d2e6675bbdf8d6f97d24728a6ae4e592_0.file.site_main.tpl.php(90): Smarty_Internal_Template->_subTemplateRender('/Users/kazz_oga...', NULL, NULL, 0, 3600, Array, 0, true)
#5 /XXXXX/data/vendor/smarty/smarty/libs/sysplugins/smarty_template_resource_base.php(123): content_623d69af4bc459_04505133(Object(Smarty_Internal_Template))
#6 /XXXXX/data/vendor/smarty/smarty/libs/sysplugins/smarty_template_compiled.php(114): Smarty_Template_Resource_Base->getRenderedTemplateCode(Object(Smarty_Internal_Template))
#7 /XXXXX/data/vendor/smarty/smarty/libs/sysplugins/smarty_internal_template.php(216): Smarty_Template_Compiled->render(Object(Smarty_Internal_Template))
#8 /XXXXX/data/vendor/smarty/smarty/libs/sysplugins/smarty_internal_template.php(385): Smarty_Internal_Template->render()
#9 /XXXXX/data/Smarty/templates_c/default/9bdf202a499da7121ffbb15e24e901f4c9c77213_0.file.site_frame.tpl.php(126): Smarty_Internal_Template->_subTemplateRender('file:./site_mai...', NULL, NULL, 0, 3600, Array, 0, false)
#10 /XXXXX/data/vendor/smarty/smarty/libs/sysplugins/smarty_template_resource_base.php(123): content_623d69af411256_54187108(Object(Smarty_Internal_Template))
#11 /XXXXX/data/vendor/smarty/smarty/libs/sysplugins/smarty_template_compiled.php(114): Smarty_Template_Resource_Base->getRenderedTemplateCode(Object(Smarty_Internal_Template))
#12 /XXXXX/data/vendor/smarty/smarty/libs/sysplugins/smarty_internal_template.php(216): Smarty_Template_Compiled->render(Object(Smarty_Internal_Template))
#13 /XXXXX/data/vendor/smarty/smarty/libs/sysplugins/smarty_internal_templatebase.php(232): Smarty_Internal_Template->render(false, 0)
#14 /XXXXX/data/vendor/smarty/smarty/libs/sysplugins/smarty_internal_templatebase.php(116): Smarty_Internal_TemplateBase->_execute(Object(Smarty_Internal_Template), NULL, NULL, NULL, 0)
#15 /XXXXX/data/class/SC_View.php(113): Smarty_Internal_TemplateBase->fetch('site_frame.tpl')
#16 /XXXXX/data/class/SC_Display.php(80): SC_View->getResponse('site_frame.tpl')
#17 /XXXXX/data/class/pages/LC_Page.php(376): SC_Display->prepare(Object(LC_Page_Contact_Ex))
#18 /XXXXX/data/class/pages/contact/LC_Page_Contact.php(68): LC_Page->sendResponse()
#19 /XXXXX/data/class_extends/page_extends/contact/LC_Page_Contact_Ex.php(54): LC_Page_Contact->process()
#20 /XXXXX/html/contact/index.php(28): LC_Page_Contact_Ex->process()
#21 {main}
thrown on [/XXXXX/data/Smarty/templates_c/default/a6b601a572db0ab44c8ea6c4be47feb33ac4074d_0.file.index.tpl.php(186)] from ::1
customer_id =