Uninitialized attribute _a1 in base_attr_nullable_alt1::Foo::run (alt/base_attr_nullable_alt1.nit:38)
,---- Stack trace -- - -  -
| base_attr_nullable_alt1::Foo::run (alt/base_attr_nullable_alt1.nit:36)
| base_attr_nullable_alt1::Foo::init (alt/base_attr_nullable_alt1.nit:48)
| base_attr_nullable_alt1::Sys::main (alt/base_attr_nullable_alt1.nit:81)
`------------------- - -  -