```python
def trace_relay(links: dict, start: str) -> list:
    if not isinstance(links, dict):
        raise ValueError("links must be a dictionary")
    
    if start not in links or links[start] != "":
        raise ValueError(f"start post '{start}' must be in links and hand off to the empty name")
    
    visited = set()
    path = [start]
    
    while start != "":
        next_post = links[start]
        
        if next_post == "" or next_post in visited:
            raise ValueError("handoffs cannot come back to a post already visited")
        
        visited.add(start)
        path.append(next_post)
        
        if not isinstance(next_post, str):
            raise ValueError(f"next post '{next_post}' is not a valid string name")
        
        start = next_post
    
    return path
```