Fix crash on changing from empty scratch buffer to itself (#975)

helix-view/src/editor.rs

@@ -240,6 +240,8 @@ pub fn switch(&mut self, id: DocumentId, action: Action) {
                 let remove_empty_scratch = !doc.is_modified()
                     // If the buffer has no path and is not modified, it is an empty scratch buffer.
                     && doc.path().is_none()
+                    // If the buffer we are changing to is not this buffer
+                    && id != doc.id
                     // Ensure the buffer is not displayed in any other splits.
                     && !self
                         .tree