```python
def line_up(links: dict[str, str], start: str) -> list[str]:
    if start not in links:
        raise ValueError("Start name not found in links")
    
    line = []
    current = start
    
    while True:
        if current in line:
            raise ValueError("Circular link detected")
        
        line.append(current)
        
        if current not in links:
            break
        
        current = links[current]
    
    return line
```