Program with unused multiport does not compile

[petervdonovan]

The following program does not compile unless // reaction(a) {==} is uncommented:

target C

reactor A {

  output[2] port: int
}

reactor B {
  input[2] a: int
  // reaction(a) {==}
}

main reactor {
  b = new B()
  a = new A()
  a.port -> b.a
}

This is the error message (the original file name was temp.lf):

/home/peter/vscode-lingua-franca/lingua-franca/test/C/src-gen/temp/temp.c:140:30: error: ‘temp_a_port_c’ undeclared (first use in this function); did you mean ‘_a_port_t’?
  140 |     temp_a_self[0]->_lf_port[temp_a_port_c]._base.source_reactor = (self_base_t*)temp_a_self[0];
      |                              ^~~~~~~~~~~~~
      |                              _a_port_t