Excluding a bridge causes error

[jcrate]

Excluding any bridge causes an error:

gems/active_scaffold-3.4.20/lib/active_scaffold/bridges.rb:52:in block in prepare_all': undefined methodinstall?' for nil:NilClass (NoMethodError)

def self.prepare_all
  return false if bridges_prepared
  bridges.keys.each do |bridge_name|
    bridge = self[bridge_name]
    bridge.prepare if bridge.install?
  end
  self.bridges_prepared = true
end

Loading the bridge ([] aliased to load) returns nil if the bridge is excluded.