Extension relies on existance of ~/.duckdb dir

[patricklucas]

It's possible that the ~/.duckdb dir doesn't exist, even when the UI extension is installed, because it may have been installed elsewhere through calling SET extension_directory = '...'.

This code in ui_extension.cpp, however, expects it to exist:

  auto &fs = FileSystem::GetFileSystem(instance);
  fs.CreateDirectory(fs.ExpandPath("~/.duckdb/extension_data"));
  fs.CreateDirectory(fs.ExpandPath("~/.duckdb/extension_data/ui"));

A quick fix would just be to add an additional call to CreateDirectory to create ~/.duckdb if it doesn't exist, though we should also consider respecting an alternate DuckDB home dir set using set home_directory = '...'.

[jraymakers]

Good point. A custom home_directory should already be handled by the implementation of ExpandPath, but a custom extension_directory is currently not handled.