Add catalog edge only if parent resource has a container

Puppet Version: 7.7.0/6.23.0
Puppet Server Version: n/a
OS Name/Version: n/a

Managing resources with generators behaves differently with puppet resource and puppet apply.

When running with puppet apply, the parent resource is always contained by something like Class[Main], so adding an edge between that and our generated resource works.

When running with puppet resource, the parent resource is not contained by anything (container_of(parent_resource) returns nil), which adds an edge with a nil vertex to the catalog. This in turn causes the run to fail with a NilClass exception when performing pre-run checks in the Transaction class, as the catalog now contains a nil vertex.

Desired Behavior:

Running the following does not error:

> touch /tmp/asd

> puppet resource tidy /tmp/asd age=0 --trace

Actual Behavior:

Running the above example gives the following error:

Error: Could not run: undefined method `pre_run_check' for nil:NilClass

/root/puppet/lib/puppet/transaction.rb:82:in `block in perform_pre_run_checks'

/root/puppet/lib/puppet/transaction.rb:78:in `each'

/root/puppet/lib/puppet/transaction.rb:78:in `perform_pre_run_checks'

/root/puppet/lib/puppet/transaction.rb:104:in `evaluate'

/root/puppet/lib/puppet/resource/catalog.rb:240:in `block (2 levels) in apply'

[snip]