fix: itests: Don't call t.Error in MineBlocks goroutine

[magik6k]

Related Issues

This is a probable cause for a lot maybe some of flakiness in all itests - https://github.com/filecoin-project/lotus/issues?q=is%3Aissue+is%3Aopen+label%3Aimpact%2Ftest-flakiness

Proposed Changes

When miner.MineOne returns an error, which can occasionally happen on normal test shutdown with unlucky timing (e.g. chain blockstore closed during a call to MinerGetBaseInfo while it is computing state), just log the error and quit.

Additional Info

Previously the call to t.Error could make the failure look very random as it is called in a goroutine, and may be called after the original calling (sub)test has already finished.

Checklist

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[arajasek]

I think this makes sense, thanks.

I'm not sure whether you intend to merge the additional logging to batch_deal_test, but I would be in favour of doing so -- this test basically fails 100% of the time, so more info good.