Don't try to MRO things that don't have one

properly declare types for these two items

Author: coke

type-graph.txt

@@ -50,6 +50,7 @@ class Attribute
 
 [Domain-specific]
 # VM
+role  Systemic
 class Distro
 class Kernel
 class VM                            does Systemic
@@ -483,4 +484,4 @@ class CX::Succeed                                  does X::Control
 class CX::Proceed                                  does X::Control
 
 [Core]
-class Test
+module Test

xt/type-graph.t

@@ -10,7 +10,7 @@ my $t = Perl6::TypeGraph.new-from-file('type-graph.txt');
 
 for $t.sorted -> $type {
     next if $type.name.index('Metamodel').defined || $type.name eq 'PROCESS';
-    next if $type.packagetype eq 'role';
+    next if $type.packagetype eq 'role'|'module';
     next if $type.name eq 'Failure';
     try {
         my $got = ~$type.mro;