overlays/iosevka: refactor patcher argument passing, use bundled nerdicons

nix/lib/mkNerdFont.nix

@@ -6,8 +6,7 @@
 }:
 {
   font,
-  extraArgs ? [ ],
-  useDefaultsArgs ? true,
+  patcherArgs ? [ ],
 }:
 stdenvNoCC.mkDerivation {
   /*
@@ -27,17 +26,15 @@ stdenvNoCC.mkDerivation {
 
   buildPhase =
     let
-      args =
-        lib.optionals useDefaultsArgs [
-          "--complete"
+      allPatcherArgs = [
         "--no-progressbars"
       ]
-        ++ extraArgs;
+      ++ patcherArgs;
     in
     ''
       mkdir -p nerd-font
       find \( -name \*.ttf -o -name \*.otf \) | parallel --jobs=$NIX_BUILD_CORES nerd-font-patcher {} \
-          --outputdir nerd-font ${builtins.concatStringsSep " " args}
+          --outputdir nerd-font ${builtins.concatStringsSep " " allPatcherArgs}
     '';
 
   installPhase = ''

nix/overlays/iosevka.nix

@@ -7,7 +7,9 @@ final: prev: rec {
     // {
       iosevka = mkNerdFont {
         font = iosevka;
-        extraArgs = [
+        patcherArgs = [
+          "--complete"
+          "--careful"
           "--name {/.}-NFM"
           "--mono"
         ];