How to get a field's parent in a custom input component in Sanity

import { ChangeIndicatorContext } from '@sanity/base/change-indicators';
// other imports

interface ModelHighlightedFieldsInputProps
  extends CustomInputComponentProps<string> {
  document: Sanity.Schema.Article;
}

type FullPath = Array<string | { _key: string }>;

interface ChangeIndicatorContextValue {
  fullPath: FullPath;
}

export const useChangeIndicator = () => {
  const ctx = React.useContext(ChangeIndicatorContext);
  if (!ctx)
    throw new Error('useSearchContext must be used within a ThemeProvider');
  return ctx as ChangeIndicatorContextValue;
};

const getParent = (
  document: Sanity.Schema.Article,
  fullPath: FullPath,
): Sanity.Schema.ModelReference => {
  return fullPath.slice(0, -1).reduce((prevValue, pathNode) => {
    if (typeof pathNode === 'string') return prevValue[pathNode];
    if (Array.isArray(prevValue)) {
      return prevValue.find((item) => item._key === pathNode._key);
    }
    throw new Error('Not sure how we got here');
  }, document);
};

const ModelHighlightedFieldsInputBase: React.FC<ModelHighlightedFieldsInputProps> =
  (props, ref) => {
    const { fullPath } = useChangeIndicator();
    const { document, type } = props;
    const parent = getParent(document, fullPath);
    // the rest of my component
  }