master doesn't build

[tellary]

Here is my output. Please let me know what additional information I should provide. Thanks!

ilya@Ilyas-Laptop reflex-dom-contrib % git log -1
commit b2c2bc3e1155e4a70d985f29cf11f66d5723b499 (HEAD -> master, origin/master, origin/HEAD)
Merge: 09d1223 135e88e
Author: Alexandre Esteves <[email protected]>
Date:   Sat Jun 4 22:12:44 2022 +0100

    Merge pull request #68 from AJChapman/reflex-0.8

    Relax version bounds to allow reflex 0.8
ilya@Ilyas-Laptop reflex-dom-contrib % nix-build -A ghc.reflex-dom-contrib
error:
       … in the left operand of the update (//) operator
         at /nix/store/xgq3r0an157dr04426rzj4p8967k8j0i-source/pkgs/development/haskell-modules/lib.nix:39:7:
           38|     mkDerivation = drv: (args.mkDerivation drv).override f;
           39|   })) // {
             |       ^
           40|     overrideScope = scope: overrideCabal (drv.overrideScope scope) f;

       … in the left operand of the update (//) operator
         at /nix/store/xgq3r0an157dr04426rzj4p8967k8j0i-source/pkgs/development/haskell-modules/lib.nix:39:7:
           38|     mkDerivation = drv: (args.mkDerivation drv).override f;
           39|   })) // {
             |       ^
           40|     overrideScope = scope: overrideCabal (drv.overrideScope scope) f;

       … while evaluating a branch condition
         at /nix/store/xgq3r0an157dr04426rzj4p8967k8j0i-source/lib/customisation.nix:72:7:
           71|     in
           72|       if builtins.isAttrs ff then (ff // {
             |       ^
           73|         override = newArgs: makeOverridable f (overrideWith newArgs);

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

       error: cannot coerce null to a string: null