Extension JavaScript Errors after Delay on ALL PAGES

[BelowZeroLH]

I get the following JavaScript errors on every page using this extension after a delay:

[url]:1 Unchecked runtime.lastError: The message port closed before a response was received.
[url]:1 Error handling response: TypeError: Cannot read property 'ok' of undefined
at restoreStateCallback (chrome-extension://fmiohbdblcemacakpnoinjmcelddpjbg/loadcss.js:21:15)

​My injection script is just CSS. This is its contents:

.chapter-img {
border: 0 !important;
}
.adult-content.censored .main-col .c-page__content {
opacity: 1 !important;
}
iframe[data-glx="yeap"], #_vdo_ads_player_ai_923, .toony-before_chapter_mb iframe, .toony-after_chapter iframe, iframe[sandbox="allow-same-origin allow-scripts allow-popups"] {
display: none !important; visibility: hidden !important;
}

Please fix this.