docs: unhandled Runtime Error in updateScrollButtonState and build warning

[moathabuhamad-cengage]

Description:

1. I randomly encounter a runtime error in the updateScrollButtonState function in scrolling through docs pages
2. remove the warning about missing dependency: 'headings' when building docs

Error Details:

Error in function updateScrollButtonState in ../../packages/react-magma-dom/dist/esm/index.js:59
Cannot read properties of null (reading 'scrollTop')

../../packages/react-magma-dom/dist/esm/index.js:59
  57 |
  58 |   function updateScrollButtonState() {
> 59 |     const { scrollTop, scrollHeight, clientHeight, scrollWidth, clientWidth } =
     |            ^
  60 |       tabsWrapperRef.current;
  61 |     let showStartScroll;
  62 |     let showEndScroll;

Warning Details

warn 
---website/react-magma-docs/src/components/SubPageTabs/index.js
 136:6  warning  React Hook React.useEffect has a missing dependency: 'headings'. Either include it or remove the dependency array  react-hooks/exhaustive-deps

[moathabuhamad-cengage]

warning will be fixed by #1548