message: fix: don't report mutations to aminoacid X
diff: @@ -97,7 +97,7 @@ namespace Nextclade {
  });
  } else {
  // TODO: we might account for ambiguous aminoacids in this condition
  - if (queryAa != refAa) {
  + if (queryAa != refAa && queryAa != Aminoacid::X) {
  // If not a gap and the state has changed, than it's a substitution
  aaSubstitutions.emplace_back(AminoacidSubstitution{
  .gene = gene.geneName,
  