message: check for existing files
diff: @@ -114,7 +114,8 @@ struct Input
  .add_option("-m,--mesh",
  meshName,
  "Surface mesh file (STL files are currently supported)")
  - ->required();
  + ->required()
  + ->check(axom::CLI::ExistingFile);
  app
  .add_flag("--distance,!--no-distance",
  @@ -130,10 +131,12 @@ struct Input
  // Note: Baselines comparisons only supported when Axom is configured with hdf5
  // Users must supply either a baseline, or both the query resolution and bounding box
  #ifdef AXOM_USE_HDF5
  - app.add_option("-b,--baseline",
  + app
  + .add_option("-b,--baseline",
  baselineRoot,
  "root file of baseline, a sidre rootfile.\n"
  - "Note: Only supported when Axom configured with hdf5");
  + "Note: Only supported when Axom configured with hdf5")
  + ->check(axom::CLI::ExistingFile);
  #endif
  // user can supply 1 or 3 values for resolution
  