Use presence to avoid vals set to empty strings.

config.ru

@@ -3,11 +3,11 @@
 require ::File.expand_path('../config/environment', __FILE__)
 
 # Redirect to the custom (canonical) hostname.
-use Rack::CanonicalHost, ENV['HOSTNAME'] if ENV['HOSTNAME']
+use Rack::CanonicalHost, ENV['HOSTNAME'] if ENV['HOSTNAME'].present?
 
 # Optional Basic Auth - Enabled if BASIC_AUTH_PASSWORD is set. User is optional (any value will be accepted).
-BASIC_AUTH_USER     = ENV['BASIC_AUTH_USER']
-BASIC_AUTH_PASSWORD = ENV['BASIC_AUTH_PASSWORD']
+BASIC_AUTH_USER     = ENV['BASIC_AUTH_USER'].presence
+BASIC_AUTH_PASSWORD = ENV['BASIC_AUTH_PASSWORD'].presence
 
 if BASIC_AUTH_PASSWORD
   use Rack::Auth::Basic do |username, password|