```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):
        name, _, qty_str = move.partition("+")
        qty = int(qty_str)
        if name == "":
            raise ValueError("move starts with + but no item name")
        if name not in held:
            held[name] = qty
        elif held[name] < qty:
            raise ValueError(f"issue of {qty} on missing or insufficiently many items: {name}")
        else:
            held[name] -= qty

    def apply_moves(held, moves):
        for move in moves.split(";"):
            if move == "":
                continue
            try:
                apply_move(held, move)
            except ValueError as e:
                raise ValueError(f"move '{move}' failed: {e}")

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