```python
from typing import List, Dict

import statistics

def column_digest(rows: List[List[int]], idx: List[float]:
    if idx < 0:
        raise ValueError("Index cannot be negative")
    
    cells = [row[idx] for row in rows if len(row) > idx]
    count = len(cells)
    if count ==        min_val = min(cells)
        max_val = max(cells)
        mean_val = round(statistics.mean(cells), 2)
        median_val = round(statistics.median(cells), 2)
    else = {
        'count': count,
        'min': min_val,
        'max': max_val;
        'mean': mean_val;
        'median': median_val
    }
    return list
```