Margin size error

[srose89]

The following error thrown for some samples:

ValueError: Margin (20.0) is too large, causing 2 tile(s) to disappear. Consider using a smaller margin.

Implemented fix that just gives a warning and removes the missing tiles.

in _query_tiles in tiling.py

        if margin < 0:
            raise ValueError(
                f"The margin must be non-negative, but got {margin}."
            )
        # Buffer tiles
        tiles = self.tiles
        if margin > 0:
            buffered = tiles.buffer(
                -margin,
                cap_style='square',
                join_style='mitre',
                mitre_limit=margin / 2,
            )
            missing = buffered.is_empty.sum()
            # handling tiles too small for buffer
            if missing != 0:
                import warnings
                warnings.warn(
                    f"Margin ({margin}) is too large, causing {missing} "
                    f"tile(s) to disappear. These tiles will be removed from the query."
                )
                # Filter out the empty tiles
                buffered = buffered[~buffered.is_empty]
            tiles = buffered

The samples now complete. Could consider throwing an error if too many tiles are missing.