<% if RailsEnvFavicon.applicable?  %>
    <% if RailsEnvFavicon.make_grayscale %>
        <%= require_asset "grayscale-favicon.js" %>
        GrayscaleFavicon.grayscale();
    <% else %>
        <%= require_asset "tinycon.min.js" %>
        Tinycon.setOptions({
          width: 8,
          height: 9,
          colour: '<%= RailsEnvFavicon.text_color %>',
          background: '<%= RailsEnvFavicon.background_color %>',
          fallback: true
        });

        Tinycon.setBubble("<%= RailsEnvFavicon.badge_label %>");
    <% end %>
<% end %>

<% if RailsEnvFavicon.applicable?  %>
    <% if RailsEnvFavicon.make_grayscale %>
        <%= require_asset "grayscale-favicon.js" %>
        GrayscaleFavicon.grayscale();
    <% else %>
        <%= require_asset "tinycon.min.js" %>
        Tinycon.setOptions({
          width: 8,
          height: 9,
          color: '<%= RailsEnvFavicon.text_color %>',
          background: '<%= RailsEnvFavicon.background_color %>',
          fallback: true
        });

        Tinycon.setBubble("<%= RailsEnvFavicon.badge_label %>");
    <% end %>
<% end %>

Fix typo color instead of colour
Fix typo color instead of colour

Doc: https://github.com/tommoor/tinycon