we was able to import our products from Sitecore Commerce to Sitecore CMS (saved as virtual items), and i would like to search for these products using the Sitecore search. So i rebuild the Sitecore_master_index using the "indexing manager" in the control panel, unfortunately the rebuild stopped by 20000 items and showed me this error

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Job started: Index_Update_IndexName=sitecore_master_index|#Exception: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.ArgumentNullException: Value cannot be null.
Parameter name: item
   at Sitecore.Diagnostics.Assert.ArgumentNotNull(Object argument, String argumentName)
   at Sitecore.Commerce.Engine.Connect.Search.Crawlers.CatalogCrawlerBase`1.GetCatalogEntityLanguages(Item item)
   at Sitecore.Commerce.Engine.Connect.Search.Crawlers.CatalogCrawlerBase`1.GetItem(TEntity catalogEntity)
   at Sitecore.Commerce.Engine.Connect.Search.Crawlers.CatalogCrawlerBase`1.Add(IProviderUpdateContext context, CancellationToken cancellationToken)
   at Sitecore.ContentSearch.FlatDataCrawler`1.RebuildFromRoot(IProviderUpdateContext context, IndexingOptions indexingOptions, CancellationToken cancellationToken)
   at Sitecore.ContentSearch.SolrProvider.SolrSearchIndex.PerformRebuild(Boolean resetIndex, Boolean optimizeOnComplete, IndexingOptions indexingOptions, CancellationToken cancellationToken)
   at Sitecore.ContentSearch.SolrProvider.SolrSearchIndex.Rebuild(Boolean resetIndex, Boolean optimizeOnComplete)
   --- End of inner exception stack trace ---
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
   at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at Sitecore.Reflection.ReflectionUtil.InvokeMethod(MethodInfo method, Object[] parameters, Object obj)
   at Sitecore.Jobs.JobRunner.RunMethod(JobArgs args)
   at (Object , Object[] )
   at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain)
   at Sitecore.Jobs.Job.DoExecute()
   at Sitecore.Jobs.Job.ThreadEntry(Object state)
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I assume that the index was crawling all the items until he started to crawl the commerce products and some items are maybe null or something like that.

I hope that someone could help me.

Thanks in advance