```python
"""
Close out a stockroom count sheet after a day's receive and issue moves.
"""

import re


def closing_sheet(opening: str, moves: str) -> str:
    if not isinstance(opening, str) or not isinstance(moves, str):
        raise ValueError("closing_sheet expects two strings")

    def parse_sheet(text):
        held = {}
        if text == "":
            return held
        for part in text.split(";"):
            name, colon, count = part.partition(":")
            if colon == "":
                raise ValueError(f"sheet entry has no colon: {part}")
            if re.fullmatch(r"[a-z]+", name) is None:
                raise ValueError(f"bad item name: {part}")
            if re.fullmatch(r"0|[1-9]\d*", count) is None:
                raise ValueError(f"bad count: {part}")
            if name in held:
                raise ValueError(f"duplicate sheet entry: {name}")
            held[name] = int(count)
        return held

    held = parse_sheet(opening)

    def apply_move(moved: str):
        name, _, qty_str = moved.partition(":")
        qty = int(qty_str)
        if name not in held:
            raise ValueError(f"issue of item not on sheet: {name}")
        current_count = held[name]
        if qty > current_count:
            raise ValueError(f"issue of more units than available: {name}:{current_count}")
        held[name] -= qty
        if held[name] == 0:
            del held[name]

    for moved in moves.split(";"):
        if moved == "":
            continue
        apply_move(moved)

    entries = []
    for name in sorted(held):
        entries.append(f"{name}:{held[name]}")
    return ";".join(entries)
```