Broken when new event on Termux

I installed khal on Termux of my Android phone (EMUI 10.0.0) via pip install khal, and created a config file following the instruction. khal calendar works.
After setting the default calendar, I tried khal new 13:30 lunch and I got these:

Traceback (most recent call last):
  File "/data/data/com.termux/files/usr/bin/khal", line 8, in <module>
    sys.exit(main_khal())
  File "/data/data/com.termux/files/usr/lib/python3.9/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/data/data/com.termux/files/usr/lib/python3.9/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/data/data/com.termux/files/usr/lib/python3.9/site-packages/click/core.py", line 1259, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/data/data/com.termux/files/usr/lib/python3.9/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/data/data/com.termux/files/usr/lib/python3.9/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/data/data/com.termux/files/usr/lib/python3.9/site-packages/click/decorators.py", line 21, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/data/data/com.termux/files/usr/lib/python3.9/site-packages/khal/cli.py", line 386, in new
    new_func(
  File "/data/data/com.termux/files/usr/lib/python3.9/site-packages/khal/controllers.py", line 353, in new_from_string
    new_from_args(
  File "/data/data/com.termux/files/usr/lib/python3.9/site-packages/khal/controllers.py", line 379, in new_from_args
    collection.new(event)
  File "/data/data/com.termux/files/usr/lib/python3.9/site-packages/khal/khalendar/khalendar.py", line 207, in new
    event.href, event.etag = self._storages[calendar].upload(event)
  File "/data/data/com.termux/files/usr/lib/python3.9/site-packages/khal/khalendar/vdir.py", line 214, in upload
    fpath, etag = self._upload_impl(item, href)
  File "/data/data/com.termux/files/usr/lib/python3.9/site-packages/khal/khalendar/vdir.py", line 233, in _upload_impl
    return fpath, get_etag_from_file(f)
  File "/data/data/com.termux/files/usr/lib/python3.9/contextlib.py", line 124, in __exit__
    next(self.gen)
  File "/data/data/com.termux/files/usr/lib/python3.9/site-packages/atomicwrites/__init__.py", line 169, in _open
    self.commit(f)
  File "/data/data/com.termux/files/usr/lib/python3.9/site-packages/atomicwrites/__init__.py", line 204, in commit
    move_atomic(f.name, self._path)
  File "/data/data/com.termux/files/usr/lib/python3.9/site-packages/atomicwrites/__init__.py", line 111, in move_atomic
    return _move_atomic(src, dst)
  File "/data/data/com.termux/files/usr/lib/python3.9/site-packages/atomicwrites/__init__.py", line 59, in _move_atomic
    os.link(src, dst)
AttributeError: module 'os' has no attribute 'link'

And the following is what I wrote in my config file:

[calendars]
[[private]]
path = ~/.config/khal/private
type = calendar
color = yellow

[default]
default_calendar = private
highlight_event_days = True

[highlight_days]
color = light blue
default_color = yellow                      
[locale]
timeformat = %H:%M
dateformat = %Y-%m-%d
longdateformat = %Y-%m-%d
datetimeformat = %Y-%m-%d %H:%M
longdatetimeformat = %Y-%m-%d %H:%M

I don't know if it is about the OS. Please help me!

Start with the traceback path through khal/controllers.py, khal/khalendar/khalendar.py, and khal/khalendar/vdir.py, then inspect the atomicwrites operation that calls os.link. Reproduce event creation on Termux and determine the project's expected handling for this unsupported operation; done should mean the behavior is resolved or clearly reported with a regression test.