refactor: fix Credo warnings in field visibility modules

Use Enum.map_join and reduce nesting in format_custom_field_label

lib/mv_web/live/components/field_visibility_dropdown_component.ex

@@ -153,20 +153,20 @@ defmodule MvWeb.Components.FieldVisibilityDropdownComponent do
     |> field_to_string()
     |> String.replace("_", " ")
     |> String.split()
-    |> Enum.map(&String.capitalize/1)
-    |> Enum.join(" ")
+    |> Enum.map_join(" ", &String.capitalize/1)
   end
 
   defp format_custom_field_label(field_string, custom_fields) do
-    case String.trim_leading(field_string, "custom_field_") do
-      "" ->
-        field_string
+    id = String.trim_leading(field_string, "custom_field_")
+    find_custom_field_name(id, field_string, custom_fields)
+  end
 
-      id ->
-        case Enum.find(custom_fields, fn cf -> to_string(cf.id) == id end) do
-          nil -> gettext("Custom Field %{id}", id: id)
-          custom_field -> custom_field.name
-        end
+  defp find_custom_field_name("", field_string, _custom_fields), do: field_string
+
+  defp find_custom_field_name(id, _field_string, custom_fields) do
+    case Enum.find(custom_fields, fn cf -> to_string(cf.id) == id end) do
+      nil -> gettext("Custom Field %{id}", id: id)
+      custom_field -> custom_field.name
     end
   end
 end

lib/mv_web/live/member_live/index/field_selection.ex

@@ -198,8 +198,7 @@ defmodule MvWeb.MemberLive.Index.FieldSelection do
   def to_url_param(selection) when is_map(selection) do
     selection
     |> Enum.filter(fn {_field, visible} -> visible end)
-    |> Enum.map(fn {field, _visible} -> field end)
-    |> Enum.join(",")
+    |> Enum.map_join(",", fn {field, _visible} -> field end)
   end
 
   def to_url_param(_), do: ""