Docker - switch // overlay / overlay2 FS lead to emergency console

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Hi,
i’m pretty new to nixos and made my first steps.
I’d installed nixos and wanted to enable docker;

  virtualisation.docker.enable = true;
  #virtualisation.docker.storageDriver = "overlay2";

which leaded after reboot to this error:
overlayfs lower directory not found.

i believe and maybe someone can assist me - that a nixos-generate-config creates the following entry which is not intended by the docker daemon

#  fileSystems."/var/lib/docker/overlay2/2759d93183010abe2e39e0516af98bb1d5cb5bdef11dc4460170c096d48e5873/merged" =
#    { device = "overlay";
#      fsType = "overlay";
#    };

which leaded to a fstab entry and then finaly into emergency console.

By deactivating this overlayfs entry in hardware-config the boot does work as expected.
Is this possible a side-effect of the generation - and should there be a warning in combination with docker? maybe ignore overlay-fs entry in a whole? a bug?

thanks for sharing your wisdom with me
Johannes