Node sometimes panics when queried

[enlight]

These panics started happening occasionally on one of the Basechain nodes that has been upgraded to build 1363:

Panic in RPC HTTP handler module=query-server err="failed to load immutable tree for version 21746299: version does not exist" stack="goroutine 614700 [running]:
	runtime/debug.Stack(0xc07a566ae0, 0x1aca2e0, 0xc0a9181d00)
	/usr/local/go-1.12/src/runtime/debug/stack.go:24 +0x9d
	github.com/loomnetwork/loomchain/vendor/github.com/tendermint/tendermint/rpc/lib/server.RecoverAndLogHandler.func1.1(0xc0a9181be0, 0x20397a0, 0xc00ec1ecb0, 0xbf8b5f7d336b17a1, 0x95adb69ba8, 0x2e87020, 0xc093a1d200)
	/tmp/gopath-jenkins-loom-sdk-pipeline3-1363/src/github.com/loomnetwork/loomchain/vendor/github.com/tendermint/tendermint/rpc/lib/server/http_server.go:134 +0x552
	panic(0x1aca2e0, 0xc0a9181d00)
	/usr/local/go-1.12/src/runtime/panic.go:522 +0x1b5
	github.com/loomnetwork/loomchain.(*Application).ReadOnlyState(0xc0002f8f00, 0xc085d51528, 0xb180ac)
	/tmp/gopath-jenkins-loom-sdk-pipeline3-1363/src/github.com/loomnetwork/loomchain/app.go:940 +0x35f
	github.com/loomnetwork/loomchain/rpc.(*QueryServer).GetEvmLogs(0xc00d38ad80, 0xc0a2a60eb0, 0x4c, 0x0, 0x0, 0x0, 0x0, 0x0)
	/tmp/gopath-jenkins-loom-sdk-pipeline3-1363/src/github.com/loomnetwork/loomchain/rpc/query_server.go:647 +0x67
	github.com/loomnetwork/loomchain/rpc.InstrumentingMiddleware.GetEvmLogs(0x2013fa0, 0xc038c12060, 0x2014020, 0xc038c12140, 0x2063660, 0xc00d38ad80, 0xc0a2a60eb0, 0x4c, 0x0, 0x0, ...)

The cause is likely not the same as in #1615