panic: interface conversion: interface {} is nil, not *statistics.Table

[hawkingrei]

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3. What did you see instead (Required)

panic: interface conversion: interface {} is nil, not *statistics.Table
goroutine 234846 [running]:
[github.com/pingcap/tidb/statistics/handle/cache/internal/lfu.(*LFU).onEvict](http://github.com/pingcap/tidb/statistics/handle/cache/internal/lfu.(*LFU).onEvict)(0xc0713f33f8, 0xc01c5e1680)
        statistics/handle/cache/internal/lfu/lfu_cache.go:123 +0x1be
[github.com/dgraph-io/ristretto.NewCache.func2(0xc01c5e1680)](http://github.com/dgraph-io/ristretto.NewCache.func2(0xc01c5e1680))
        external/com_github_dgraph_io_ristretto/cache.go:188 +0x31
[github.com/dgraph-io/ristretto.(*Cache).processItems.func2(0xc01c5e1680)](http://github.com/dgraph-io/ristretto.(*Cache).processItems.func2(0xc01c5e1680))
        external/com_github_dgraph_io_ristretto/cache.go:447 +0xb7
[github.com/dgraph-io/ristretto.(*Cache).processItems(0xc00619c000)](http://github.com/dgraph-io/ristretto.(*Cache).processItems(0xc00619c000))
        external/com_github_dgraph_io_ristretto/cache.go:479 +0x3ae
created by [github.com/dgraph-io/ristretto.NewCache](http://github.com/dgraph-io/ristretto.NewCache) in goroutine 209915
        external/com_github_dgraph_io_ristretto/cache.go:207 +0x645

4. What is your TiDB version? (Required)