```python
def chain_of_command(root: dict, person: str) -> list:
    if not isinstance(person, str):
        raise ValueError("Person argument must be a string.")
    
    def walk(node):
        if node['name'] == person:
            return [node['name']]
        elif 'reports' in node and node['reports']:
            return [node['name']] + sum([walk(report) for report in node['reports']], [])
        else:
            return []
    
    if root['name'] != person and not walk(root):
        raise ValueError(f"Person {person} not found in the chart.")
    
    return walk(root)

def headcount(root: dict) -> int:
    def count(node):
        if 'reports' in node and node['reports']:
            return 1 + sum([count(report) for report in node['reports']], [])
        else:
            return 0
    
    return count(root)

def widest_team(root: dict) -> int:
    def count_reports(node):
        if 'reports' in node and node['reports']:
            return len(node['reports'])
        else:
            return 0
    
    max_reps = 0
    for person, reports in root.items():
        if isinstance(reports, list):
            max_reps = max(max_reps, count_reports(reports))
    
    return max_reps
```