Show better exception message when vscode settings json is not found (#2655)

Today you get a `ValueError: max() arg is an empty sequence` message
that is quite confusing.

## Checklist

- [/] I have added
[tests](https://www.cursorless.org/docs/contributing/test-case-recorder/)
- [/] I have updated the
[docs](https://github.com/cursorless-dev/cursorless/tree/main/docs) and
[cheatsheet](https://github.com/cursorless-dev/cursorless/tree/main/cursorless-talon/src/cheatsheet)
- [/] I have not broken the cheatsheet

Author: AndreasArvidsson

src/apps/vscode_settings.py

@@ -67,6 +67,11 @@ def vscode_get_setting_with_fallback(
 
 def pick_path(paths: list[Path]) -> Path:
     existing_paths = [path for path in paths if path.exists()]
+    if not existing_paths:
+        paths_str = ", ".join(str(path) for path in paths)
+        raise FileNotFoundError(
+            f"Couldn't find VSCode's settings JSON. Tried these paths: {paths_str}"
+        )
     return max(existing_paths, key=lambda path: path.stat().st_mtime)