```ts
/** How many of a store's values reach a floor. */
export function overCount(
  store: Record<string, number>,
  floor: number,
): number {
  if (typeof store !== 'object' || !(store instanceof Object)) {
    throw new Error('Input must be an object');
  }
  let found = 0;
  for (const key of Object.keys(store)) {
    if (typeof store[key] === 'number' && store[key] < floor) {
      found += 1;
    }
  }
  return found;
}
```