message: add info about CIF export failure
diff: @@ -50,7 +50,14 @@ function _exportHierarchy(plugin: PluginContext, options?: { format?: 'cif' | 'b
  await new Promise(res => setTimeout(res, 50));
  }
  + try {
  files.push([name, to_mmCIF(s.model.entryId, s, format === 'bcif', { copyAllCategories: true })]);
  + } catch (e) {
  + if (format === 'cif' && s.elementCount > 2000000) {
  + plugin.log.warn(`[Export] The structure might be too big to be exported as Text CIF, consider using the BinaryCIF format instead.`);
  + }
  + throw e;
  + }
  }
  if (files.length === 1) {
  