Random test failure, syncing beyond genesis

[Kubuxu]

    sync_test.go:172: 
        	Error Trace:	sync_test.go:172
        	            				sync_test.go:130
        	            				sync_test.go:506
        	            				sync_test.go:800
        	Error:      	Received unexpected error:
        	            	sync to submitted block failed:
        	            	    github.com/filecoin-project/lotus/node/impl/full.(*SyncAPI).SyncSubmitBlock
        	            	        /home/circleci/project/node/impl/full/sync.go:89
        	            	  - collectChain failed:
        	            	    github.com/filecoin-project/lotus/chain.(*Syncer).Sync
        	            	        /home/circleci/project/chain/sync.go:580
        	            	  - failed to load next local tipset:
        	            	    github.com/filecoin-project/lotus/chain.(*Syncer).collectHeaders
        	            	        /home/circleci/project/chain/sync.go:1395
        	            	  - get block bafyreiaqpwbbyjo4a42saasj36kkrpv4tsherf2e7bvezkert2a7dhonoi:
        	            	    github.com/filecoin-project/lotus/chain/store.(*ChainStore).LoadTipSet.func1
        	            	        /home/circleci/project/chain/store/store.go:548
        	            	  - cbor input should be of type array
        	Test:       	TestSyncCheckpointEarlierThanHead

[Kubuxu]

Similar error in pledge sector:

failed to submit newly mined block: sync to submitted block failed: collectChain failed: failed to load next local tipset: get block bafyreiaqpwbbyjo4a42saasj36kkrpv4tsherf2e7bvezkert2a7dhonoi: cbor input should be of type array
    util.go:73: block never managed to sync to node

[Kubuxu]

Similar error in TestAPI/id:

miner	miner/miner.go:283	failed to submit newly mined block: sync to submitted block failed: collectChain failed: failed to load next local tipset: get block bafyreiaqpwbbyjo4a42saasj36kkrpv4tsherf2e7bvezkert2a7dhonoi: cbor input should be of type array
    util.go:73: block never managed to sync to node

[dirkmc]

I'm seeing these errors in tests all over the place

[dirkmc]

submitted block failed: collectChain failed: failed to load next local tipset: get block bafyreiaqpwbbyjo4a42saasj36kkrpv4tsherf2e7bvezkert2a7dhonoi: cbor input should be of type array

https://app.circleci.com/pipelines/github/filecoin-project/lotus/10964/workflows/8dbcec09-1c0e-4fd7-b7e1-7d4d3a69a532/jobs/81698

[Kubuxu]

Reproduction: go test -v -run TestAPI/id -count 100 -failfast ./node

[schomatis]

Fixed by @Kubuxu, we're ignoring the possibility of null blocks in the sync logic and may request more than needed.