FormatCode adds line filled with spaces when run on .cc file

**Description**

Running `:FormatCode` on a cpp source (not header) file causes a trailing line filled with whitespaces to appear at the end of the document.
Running `:FormatCode` again and again removes and re-adds and removes and ... this line.

**Steps to reproduce**

1) Use this init.vim file:

```
call plug#begin('~/.local/share/nvim/plugged-minimal')
Plug 'google/vim-maktaba' " Needed for vim-codefmt
Plug 'google/vim-glaive' " Needed for vim-codefmt
Plug 'google/vim-codefmt' " Code formatting
call plug#end()
```

2) Open any .cc file (for example I use `base/run_loop.cc` from the chromium project

3) Run `:FormatCode`. Observe line with trailing whitespaces at the end of the file
4) Run `:FormatCode`. Observe line with trailing whitespaces at the end of the file is gone.
5) Repeat

**My Setup**

* 'vim-codefmt' is up-to-date (I ran `:PlugUpdate`)

```
─❯ nvim --version
NVIM v0.7.2
```

```
╰─❯ clang-format --version
clang-format version google3-trunk (30af2fb33ed2f610abfa50e53df9712887b2bd25)
```

**Gif of the bug**


**Other things I tried**

* Manually running `clang-format -i base/run_loop.cc` from the command line **does not introduce these whitespaces**, which is why I opened the bug against `vim-codefmt` and not `clang-format`.

Please let me know if you need any more information.

Thanks!