I tried to run Unicycler on a Virtual Box with Ubuntu 16.04, but it crashed during Pilon polish. Any idea what went wrong? Is it possible to continue the assembly, and only do the polishing?

Traceback (most recent call last): File "/usr/local/bin/unicycler", line 9, in <module> load_entry_point('unicycler==0.4.3', 'console_scripts', 'unicycler')() File "/usr/local/lib/python3.5/dist-packages/unicycler/unicycler.py", line 212, in main final_polish(graph, args, counter, long_reads_available) File "/usr/local/lib/python3.5/dist-packages/unicycler/unicycler.py", line 925, in final_polish polish_with_pilon_multiple_rounds(graph, graph, args, polish_dir, do_pilon_reassembly) File "/usr/local/lib/python3.5/dist-packages/unicycler/pilon_func.py", line 64, in polish_with_pilon_multiple_rounds insert_size_99th, i+1, fix_type) File "/usr/local/lib/python3.5/dist-packages/unicycler/pilon_func.py", line 335, in polish_with_pilon os.remove(f) OSError: [Errno 26] Text file busy: '1_pilon.changes'