```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_moves(held, move_text):
        for part in move_text.split(";"):
            action, sep, amount_str = part.partition("+")
            if sep == "":
                action, sep, amount_str = part.partition("-")
                if sep != "-":
                    raise ValueError(f"malformed move: {part}")
                amount = int(amount_str)
                if amount <= 0:
                    raise ValueError(f"negative issue quantity: {part}")
                if action not in held or held[action] < amount:
                    raise ValueError(f"insufficient stock to issue {amount} of {action}: {part}")
                held[action] -= amount
            else:
                amount = int(amount_str)
                if amount <= 0:
                    raise ValueError(f"non-positive receive quantity: {part}")
                if action in held:
                    raise ValueError(f"duplicate item in moves: {part}")
                held[action] = amount

    held = parse_sheet(opening)
    apply_moves(held, moves)
    entries = []
    for name in sorted(held):
        if held[name] > 0:
            entries.append(f"{name}:{held[name]}")
    return ";".join(entries)
```