Bug: Gui crashes when emptying quantity field

Hey Nomad,

if i make a editquanitity empty again it breaks:

ERROR    nomad.processing     2023-02-24T21:33:52 process failed
  - exception: Traceback (most recent call last):
      File "/home/a2853/Documents/Projects/nomad/nomad-FAIR/nomad/processing/data.py", line 1155, in parsing
        parser.parse(self.mainfile_file.os_path, self._parser_results, logger=logger, **kwargs)
      File "/home/a2853/Documents/Projects/nomad/nomad-FAIR/nomad/parsing/parser.py", line 484, in parse
        self.parse_file(mainfile, f, archive, logger)
      File "/home/a2853/Documents/Projects/nomad/nomad-FAIR/nomad/parsing/parser.py", line 478, in parse_file
        archive.m_update_from_dict(archive_data)
      File "/home/a2853/Documents/Projects/nomad/nomad-FAIR/nomad/datamodel/datamodel.py", line 937, in m_update_from_dict
        super().m_update_from_dict(dct)
      File "/home/a2853/Documents/Projects/nomad/nomad-FAIR/nomad/metainfo/metainfo.py", line 2208, in m_update_from_dict
        sub_section_value, m_parent=self, m_context=m_context)
      File "/home/a2853/Documents/Projects/nomad/nomad-FAIR/nomad/metainfo/metainfo.py", line 2248, in m_from_dict
        return MSection.from_dict(data, cls=cls, **kwargs)
      File "/home/a2853/Documents/Projects/nomad/nomad-FAIR/nomad/metainfo/metainfo.py", line 2313, in from_dict
        section.m_update_from_dict(dct)
      File "/home/a2853/Documents/Projects/nomad/nomad-FAIR/nomad/metainfo/metainfo.py", line 2208, in m_update_from_dict
        sub_section_value, m_parent=self, m_context=m_context)
      File "/home/a2853/Documents/Projects/nomad/nomad-FAIR/nomad/metainfo/metainfo.py", line 2248, in m_from_dict
        return MSection.from_dict(data, cls=cls, **kwargs)
      File "/home/a2853/Documents/Projects/nomad/nomad-FAIR/nomad/metainfo/metainfo.py", line 2313, in from_dict
        section.m_update_from_dict(dct)
      File "/home/a2853/Documents/Projects/nomad/nomad-FAIR/nomad/metainfo/metainfo.py", line 2234, in m_update_from_dict
        section.__dict__[property_def.name] = self.__deserialize(section, quantity_def, quantity_value)
      File "/home/a2853/Documents/Projects/nomad/nomad-FAIR/nomad/metainfo/metainfo.py", line 2165, in __deserialize
        return tgt_type(quantity_value)
    TypeError: int() argument must be a string, a bytes-like object or a number, not 'NoneType'
  - exception_hash: XWv0-WBM9gZDFAH2y1_hPJcfECQ0
  - nomad.commit: 
  - nomad.deployment: devel
  - nomad.entry_id: zKFPUKjiUeIT9gshEOnpZ2U_JSc4
  - nomad.mainfile: sample.archive.json
  - nomad.processing.error: int() argument must be a string, a bytes-like object or a number, not 'NoneType'
  - nomad.processing.errors: parser failed with exception
  - nomad.processing.logger: nomad.processing
  - nomad.processing.parser: parsers/archive
  - nomad.processing.proc: Entry
  - nomad.processing.process: process_entry_local
  - nomad.processing.process_status: RUNNING
  - nomad.processing.process_worker_id: Z-GGvhFYR5estUBzgZY8sA
  - nomad.processing.step: parsers/archive
  - nomad.service: app
  - nomad.upload_id: jNIJKiLTSRy4aQfbFOmA3Q
  - nomad.version: 1.1.7.dev368+g21f8058a2.d20230224

simplescreenrecorder-2023-02-24_22.38.35

Best Micha

part of #1493 (closed)