Dgraph panic: interface conversion: interface {} is string, not int64

Various types of erroneous problems often occur in our cluster, but we can’t find the cause of the trigger。
May I ask what the following questions are?
Such as:

  panic: interface conversion: interface {} is string, not int64 
/home/user/panorama-dgraph-images/dgraph/tok/tok.go:194
	github.com/dgraph-io/dgraph/tok.BuildTokens(0x1eb51e0, 0xc00037ed30, 0x23b5590, 0x338edc0, 0x23b5590, 0x338edc0, 0xc00037ed30, 0x0, 0x0)
	/home/user/dgraph/worker/executor.go:120 +0x53d
	/home/user/dgraph/worker/executor.go:279 +0x130
	/home/user/dgraph/tok/tok.go:108 +0x63
github.com/dgraph-io/dgraph/worker.generateTokenKeys(0xc0017d4000, 0xc00037ed10, 0x1, 0x1, 0x12, 0xc00037ed00, 0x1, 0x1, 0xc006fc8740)
github.com/dgraph-io/dgraph/worker.generateTokenKeys(0xc0017d4000, 0xc00037ed10, 0x1, 0x1, 0x12, 0xc00037ed00, 0x1, 0x1, 0xc006fc8740)
github.com/dgraph-io/dgraph/worker.generateConflictKeys(0x23ab7e0, 0xc00004a080, 0xc00695ea00, 0x0)
github.com/dgraph-io/dgraph/worker.(*executor).processMutationCh(0xc0003e27d0, 0x23ab7e0, 0xc00004a080, 0xc00030b380)
/home/user/panorama-dgraph-images/dgraph/worker/executor.go:220 +0x46d

What version? this is an old issue that exists in some old version. But it also could be a wrong value type in the dataset not corroborating with the schema.

v20.11.2,I have no way of knowing when it will happen