```python
from typing import List, Dict

def count_by(records: List[dict], field: str) -> Dict[str, int]:
    if not field:
        raise ValueError("Field name cannot be empty text.")
    
    result = {}
    for record in records:
        value = record.get(field)
        if value is None:
            continue
        result[value] = result.get(value, 0) + 1
    
    return result
```