Issue with Makefile?

[typoworx-de]

I'm tring to build a debian package using checkinstall. It fails with this error and I think there's a little bug in the install script:

========================= Installation results ===========================
Making install in .
make[1]: Entering directory '/build/network-manager-wireguard'
make[2]: Entering directory '/build/network-manager-wireguard'
 /usr/bin/mkdir -p '/usr/lib/NetworkManager'
  /bin/bash ./libtool   --mode=install /usr/bin/install -c src/nm-wireguard-service auth-dialog/nm-wireguard-auth-dialog '/usr/lib/NetworkManager'
libtool: install: /usr/bin/install -c src/nm-wireguard-service /usr/lib/NetworkManager/nm-wireguard-service
libtool: install: /usr/bin/install -c auth-dialog/nm-wireguard-auth-dialog /usr/lib/NetworkManager/nm-wireguard-auth-dialog
 /usr/bin/mkdir -p '/usr/share/appdata'
 /usr/bin/install -c -m 644 appdata/network-manager-wireguard.metainfo.xml '/usr/share/appdata'
/usr/bin/install: cannot create regular file '/usr/share/appdata': File exists <----- NOTE THIS!
make[2]: *** [Makefile:1589: install-appdataDATA] Error 1
make[2]: Leaving directory '/build/network-manager-wireguard'
make[1]: *** [Makefile:2144: install-am] Error 2
make[1]: Leaving directory '/build/network-manager-wireguard'
make: *** [Makefile:1679: install-recursive] Error 1

****  Installation failed. Aborting package creation.

Shouldn't this line:
/usr/bin/install -c -m 644 appdata/network-manager-wireguard.metainfo.xml '/usr/share/appdata'

look like this to point to appdata as directory? It looks like install command tries to override appdata as file
/usr/bin/install -c -m 644 appdata/network-manager-wireguard.metainfo.xml '/usr/share/appdata/'

or shouldn't Makefile:install make shure the path exists?
mkdir -p /usr/share/appdata?