Fails on old version

[iaaka]

Hi @prete, thank you for this tool, it works well for newer files (at least for version 6.2.1) but fails on older (at least on v5.1.0), for example this nfs/cellgeni/pasham/code/cloupe/data/labelled_cloupe_upload/bayanne_cloupe_upload/WS_D_SKNsp10264999_PL.cloupe (or any in same folder):

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[67], line 2
      1 file_path = '/nfs/cellgeni/pasham/code/cloupe/data/labelled_cloupe_upload/bayanne_cloupe_upload/WS_D_SKNsp10264999_PL.cloupe'
----> 2 cloupe = Cloupe(file_path)

Cell In[4], line 28, in Cloupe.__init__(self, cloupe_path)
     25 for run in self.index_block.get("Runs", []):
     26     if "Metadata" in run:
     27         run["Metadata"] = self.read_block(
---> 28             start=run["Metadata"]["Start"],
     29             end=run["Metadata"]["End"],
     30             as_json=True,
     31         )
     32     self.runs.append(run)
     34 # read Metrics

TypeError: 'NoneType' object is not subscriptable