error:
       … while evaluating a branch condition
         at «string»:25:5:
           24|     v:
           25|     if !builtins.isAttrs v || isDrv v then
             |     ^
           26|       v

       … in the left operand of the OR (||) operator
         at «string»:25:28:
           24|     v:
           25|     if !builtins.isAttrs v || isDrv v then
             |                            ^
           26|       v

       … while evaluating definitions from `/nix/store/9iv83r72z5xwgylkwms1qip1ijnr6jqs-source/modules/transposition.nix':

       … while evaluating definitions from `/nix/store/pvxwgpmpbqfy3i4sm37kk8g8s3d3l8j3-source/flake.nix, via option perSystem':

       … while evaluating the option `system.build.toplevel':

       … while evaluating definitions from `/nix/store/b8xf6hsi4wfakzvn6lsi040bh9n8djcc-source/nixos/modules/system/activation/top-level.nix':

       (stack trace truncated; use '--show-trace' to show the full, detailed trace)

       error:
       Failed assertions:
       - The option definition `hardware.raspberry-pi."4".poe-plus-hat' in `/nix/store/pvxwgpmpbqfy3i4sm37kk8g8s3d3l8j3-source/hosts/gaia/fan-control.nix' no longer has any effect; please remove it.
       Use the stock rpi-poe-plus firmware overlay instead:

         hardware.raspberry-pi.configtxt.deviceTreeOverlays."board-type=0x11" = [
           {
             rpi-poe-plus = {
               poe_fan_temp0 = 40000;
               poe_fan_temp0_hyst = 2000;
               poe_fan_temp1 = 45000;
               poe_fan_temp1_hyst = 2000;
               poe_fan_temp2 = 50000;
               poe_fan_temp2_hyst = 2000;
               poe_fan_temp3 = 55000;
               poe_fan_temp3_hyst = 5000;
             };
           }
         ];

       These are the overlay defaults. Parameters that were not customized can
       be omitted.


       - The option definition `hardware.raspberry-pi."4".dwc2' in `/nix/store/pvxwgpmpbqfy3i4sm37kk8g8s3d3l8j3-source/hosts/gaia/gaia1.nix' no longer has any effect; please remove it.
       Use the stock dwc2 firmware overlay instead:

         {
           boot.loader.generic-extlinux-compatible.useGenerationDeviceTree =
             false;

           hardware.raspberry-pi.configtxt.deviceTreeOverlays.pi4 = [
             { dwc2 = { }; }
           ];
         }

       If you set dr_mode on the old option, add it to the overlay. For
       example:

         { dwc2.dr_mode = "host"; }

       For CM4 and firmware-partition setup, see "DWC2 USB controller" in
       raspberry-pi/README.md.