LeafletEditor.remove() crashes if no edits were made

Issue

`LeafletEditor.remove()` calls `self.saveButton.remove()` unconditionally, but `self.saveButton` is only created when `_showSaveButton()` is called (i.e., after the user creates, edits, or deletes a feature). If `remove()` is called before any edits were made, it crashes with `TypeError: Cannot read properties of undefined (reading 'remove')`.

Steps to reproduce

1. Initialize the LeafletEditor on a GeoJSON page
2. Call `editor.remove()` without making any edits

Expected behavior

`remove()` should clean up gracefully regardless of whether edits were made.

Actual behavior

`TypeError: Cannot read properties of undefined (reading 'remove')` — the draw controls and GeoJSON layer are never cleaned up because the error occurs before `self.geoJsonLayer.remove()`.

Start at LeafletEditor.remove() and compare its cleanup sequence with _showSaveButton(), which creates saveButton. Reproduce by initializing the editor and calling remove() before any edits; done means removal completes without a TypeError and the draw controls and GeoJSON layer are cleaned up.