Broken .desktop file for racket

[y-usuzumi]

Describe the bug
After installing nixos.pltScheme, One cannot run the DrRacket from the desktop menu.

To Reproduce
Steps to reproduce the behavior:

1. Take KDE for example, open the kickoff menu
2. Search 'DrRacket'
3. Hit Enter
4. An error dialog is shown:

Expected behavior
DrRacket should run successfully.

Additional context
So the error message leads to the Exec key in the desktop file:

Exec=../../bin/drracket -singleInstance %F

which is relative to the .desktop file, but it really should be an absolute path or simply "drracket ...".

Metadata

• system: "x86_64-linux"
• host os: Linux 5.4.25, NixOS, 20.09pre217446.ddf87fb1baf (Nightingale)
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.3.3
• channels(root): "nixos-20.09pre217446.ddf87fb1baf"
• channels(kj): ""
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos

Maintainer information:

# a list of nixpkgs attributes affected by the problem
attribute:
# a list of nixos modules affected by the problem
module:

[stale]

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