fix(extract): safely remove extract directory

The previous code would remove the extract directory if the command failed.
This could be bad because we're not checking if the extract directory
already existed (since we're using `mkdir -p`), so it could be possible
that the extract operation failed, and we'd be removing a directory that
already existed and had files in it.

This change only removes the directory if there are no files in it, regardless
of whether the extract operation was successful or not. This is much safer.

plugins/extract/extract.plugin.zsh

@@ -88,9 +88,7 @@ EOF
     shift
 
     # Go back to original working directory
-    # and remove extraction directory if there was an error
     builtin cd -q "$pwd"
-    (( success > 0 )) && command rm -r "$extract_dir"
 
     # If content of extract dir is a single directory, move its contents up
     # Glob flags:
@@ -102,6 +100,8 @@ EOF
     if [[ ${#content} -eq 1 && -d "${content[1]}" ]]; then
       command mv -f "${content[1]}" .
       command rmdir "$extract_dir"
+    elif [[ ${#content} -eq 0 ]]; then
+      command rmdir "$extract_dir"
     fi
   done
 }