overlays: add overlay for elm to remove colors

overlays/default.nix

@@ -5,6 +5,14 @@ let
 
 in {
   nixpkgs.overlays = if isUnstable then [
+    (_: super: {
+      elmPackages = super.elmPackages // {
+        elm =
+          super.elmPackages.elm.override {
+            patches = [ ./elm-no-color.diff ];
+          };
+      };
+    })
     (import ./jetbrains.nix)
     (import ./tidal-hifi.nix { inherit lib; })
     openssh

overlays/elm-no-color.diff

@@ -0,0 +1,12 @@
+diff --git a/compiler/src/Reporting/Doc.hs b/compiler/src/Reporting/Doc.hs
+index 26c15517..95dbae4e 100644
+--- a/compiler/src/Reporting/Doc.hs
++++ b/compiler/src/Reporting/Doc.hs
+@@ -404,7 +404,6 @@ encodeChunks (Style bold underline color) revChunks =
+       E.object
+         [ "bold" ==> E.bool bold
+         , "underline" ==> E.bool underline
+-        , "color" ==> maybe E.null encodeColor color
+         , "string" ==> E.chars chars
+         ]
+