Make sure the install generator will fail if an error occurs

Otherwise it will exit with 0 in any case.

Author: elia

lib/solidus_dev_support/templates/extension/lib/generators/%file_name%/install/install_generator.rb.tt

@@ -6,6 +6,10 @@ module <%= class_name %>
       class_option :auto_run_migrations, type: :boolean, default: false
       source_root File.expand_path('templates', __dir__)
 
+      def self.exit_on_failure?
+        true
+      end
+
       def copy_initializer
         template 'initializer.rb', 'config/initializers/<%= file_name %>.rb'
       end