message: [EditLine] Check string pointers before dereferencing them.
  <rdar://problem/50875178>
diff: @@ -874,10 +874,11 @@ static void PrintCompletion(FILE *output_file, size_t start, size_t end,
  const char *completion_str = completions.GetStringAtIndex(i);
  const char *description_str = descriptions.GetStringAtIndex(i);
  + if (completion_str)
  fprintf(output_file, "\n\t%-*s", max_len, completion_str);
  // Print the description if we got one.
  - if (strlen(description_str))
  + if (description_str && strlen(description_str))
  fprintf(output_file, " -- %s", description_str);
  }
  }
  