```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

    def apply_move(held, move):
        if not isinstance(move, str):
            raise ValueError("move must be a string")
        if move == "":
            return held
        for part in move.split(";"):
            name, colon, qty_str = part.partition(":")
            if colon == "" or qty_str == "":
                raise ValueError(f"move entry has no colon or quantity: {part}")
            try:
                qty = int(qty_str)
                if qty <= 0:
                    raise ValueError("quantity must be a positive integer")
            except ValueError as e:
                raise ValueError(f"invalid quantity in move: {qty_str}") from e
            if name not in held:
                raise ValueError(f"move issues item not on sheet: {name}")
            count = held[name]
            if qty > count:
                raise ValueError(f"move issues more than available: {name} - {count} < {qty}")
            held[name] -= qty

    held = parse_sheet(opening)
    apply_move(held, moves)
    # Render only entries still on hand.
    entries = [f"{name}:{held[name]}" for name in sorted(held) if held[name] > 0]
    return ";".join(entries)
```