%Error: t/t_inst_missing_dot_bad.v:9:22: Dotted reference to instance that refers to missing module/interface: 'missing'
    9 |       $display("a=", missing.a);
      |                      ^~~~~~~
        ... See the manual at https://verilator.org/verilator_doc.html?v=latest for more assistance.
%Error: t/t_inst_missing_dot_bad.v:9:30: Can't find definition of 'a' in dotted variable/method: 'missing.a'
    9 |       $display("a=", missing.a);
      |                              ^
%Error: Exiting due to