```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(sheet, moves):
        if moves == "":
            return sheet
        for move in moves.split(";"):
            name, qty = move.split("+") if "+" in move else move.split("-")
            if name not in sheet:
                raise ValueError(f"issue of item not on sheet: {name}")
            if qty < 0:
                raise ValueError(f"negative quantity in move: {move}")
            if qty > sheet[name]:
                raise ValueError(f"issue of more units than available: {move}")
            sheet[name] += int(qty) if "+" in move else -int(qty)
            if sheet[name] == 0:
                del sheet[name]
        return sheet

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