```python
"""Melt a row of ice one simultaneous step at a time."""


def thaw_row(row: str, steps: int) -> str:
    if not isinstance(row, str) or not row:
        raise ValueError("thaw_row expects a non-empty string row")
    if steps < 0 or not isinstance(steps, int):
        raise ValueError("thaw_row expects a non-negative integer steps")
    if not all(c in ("#", ".") for c in row):
        raise ValueError("thaw_row expects a string row consisting only of '#' and '.'")

    if steps == 0:
        return row

    new_row = []
    for i in range(len(row)):
        if i == 0 or i == len(row) - 1 or row[i - 1] == "#" or row[i + 1] == "#":
            new_row.append(".")
        else:
            new_row.append("#")

    return "".join(new_row)
```