When select  objects to customize, the application hangs, stays in processing status, and shows error below. Could you help me please?

*I searched, but did not find any .bak files in the module

Error:  Error:  “java.lang.NullPointerException
    at java.base/java.util.Objects.requireNonNull(Objects.java:222)
    at java.base/java.util.ImmutableCollections$AbstractImmutableList.indexOf(ImmutableCollections.java:166)
    at java.base/java.util.ImmutableCollections$AbstractImmutableList.contains(ImmutableCollections.java:197)
    at ifs.dev.nb.project.api.BuildHomeFileCacheManager.queryFileInfoImpl(BuildHomeFileCacheManager.java:345)
    at ifs.dev.nb.project.api.BuildHomeFileCacheManager.queryFileInfo(BuildHomeFileCacheManager.java:287)
    at ifs.dev.nb.project.ui.explorer.SecondaryLocationIx$SecondaryLocationComponentChildFactory.createKeys(SecondaryLocationIx.java:478)
    at org.openide.nodes.AsynchChildren.run(AsynchChildren.java:190)
    at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1418)
    at org.netbeans.modules.openide.util.GlobalLookup.execute(GlobalLookup.java:45)
    at org.openide.util.lookup.Lookups.executeWith(Lookups.java:278)
ucatch] at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2033)”