`puppi` 2.2.9 breaks catalogues with `instance?' for String:Class error

[ElvenSpellmaker]

Expected Behavior

Catalogues to compile

Actual Behavior

Info: Loading facts
Error: Could not retrieve catalog from remote server: Error 500 on SERVER: Server Error: Evaluation Error: Error while evaluating a Resource Statement, Evaluation Error: Error while evaluating a Function Call, undefined method `instance?' for String:Class at /etc/puppetlabs/code/modules/yum/manifests/init.pp:167:27 at /etc/puppetlabs/code/modules/yum/manifests/repo/epel.pp:64 on node foo.com

Steps to Reproduce the Problem

1. Use an example42 module without pinning puppi in your main Puppetfile to get the latest 2.2.9 version of puppi.

Specifications

Please add this info:

1. Output of facter -p on the failing node (at least the OS related facts): N/A (all CentOS nodes we have fail)
2. Version of Puppet and of the module

• Puppet: 4.10.0
• puppi: 2.2.9

1. The relevant Puppet code and eventually Hiera data: example42/yum in init.pp, when calling params_lookup.

This is what changed when I pinned back to 2.2.6:

[hawkeye-7]

I have the same problem.

[alvagante]

2.2.7 introduces the change, it would be very useful the log of the puppetserver when failing to compile.

[alvagante]

I was able to reproduce, for the moment I reverted that change, introduced to remove some warnings.