Memory FS: Handle non-existent path in ls (#2255)
Memory FS: Handle non-existent path in ls (#2255)

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TYPE: BUG
DESC: Fix a segfault on `VFS::ls` for the in-memory filesystem

Co-authored-by: Joe Maley <16a9a54ddf4259952e3c118c763138e83693d7fd@tiledb.com>
TileDB-Inc/TileDB,TileDB-Inc/TileDB,TileDB-Inc/TileDB,TileDB-Inc/TileDB