```ruby
class ApplicationHelper::Button::CloudVolumeNew < ApplicationHelper::Button::ButtonNewDiscover
  def calculate_properties
    super
    if disabled?
      self[:title] = _("No cloud providers support creating cloud volumes.")
    end
  end

  def role_allows_feature?
    super && role_allows?(:feature => 'cloud_tenant_show_list')
  end

  # disable button if no active providers support create action
  def disabled?
    ExtManagementSystem.none? do |ems|
      Module.const_defined?("#{ems.class}::CloudVolume") &&
        ems.class::CloudVolume.supports_create?
    end
  end
end
```

Fix CloudVolume constantization issues by using try/safe_constantize
user
```ruby
class ApplicationHelper::Button::CloudVolumeNew < ApplicationHelper::Button::ButtonNewDiscover
  def calculate_properties
    super
    if disabled?
      self[:title] = _("No cloud providers support creating cloud volumes.")
    end
  end

  def role_allows_feature?
    super && role_allows?(:feature => 'cloud_tenant_show_list')
  end

  # disable button if no active providers support create action
  def disabled?
    ExtManagementSystem.none? do |ems|
      "#{ems.class}::CloudVolume".safe_constantize.try(:supports_create?)
    end
  end
end
```
assistant