message: `export`: When package name is invalid, error out earlier and with a better message
diff: @@ -288,7 +288,7 @@ namespace vcpkg::Dependencies
  if (auto spgh = maybe_spgh.get())
  return ExportPlanAction{spec, {nullopt, nullopt, *spgh}, request_type};
  - return ExportPlanAction{spec, {nullopt, nullopt, nullopt}, request_type};
  + Checks::exit_with_message(VCPKG_LINE_INFO, "Could not find package %s", spec);
  }
  };
  