Ensure Block Processing Failures Return an Error

[rauljordan]

No tracking issue. We have a problem in which the following code in block_processing.go in our blockchain package would not return an error if it failed:

beaconState, err = c.ApplyBlockStateTransition(ctx, block, beaconState)
	if err != nil {
		switch err.(type) {
		case *BlockFailedProcessingErr:
			// If the block fails processing, we mark it as blacklisted and delete it from our DB.
			c.beaconDB.MarkEvilBlockHash(blockRoot)
			if err := c.beaconDB.DeleteBlock(block); err != nil {
				return nil, fmt.Errorf("could not delete bad block from db: %v", err)
			}
		default:
			return beaconState, fmt.Errorf("could not apply block state transition: %v", err)
		}
	}

[prestonvanloon]

Any regression test?

[rauljordan]

on it

[codecov]

Codecov Report

Merging #2325 into master will increase coverage by 0.33%.
The diff coverage is 50%.

@@            Coverage Diff             @@
##           master    #2325      +/-   ##
==========================================
+ Coverage   68.44%   68.78%   +0.33%     
==========================================
  Files         118      117       -1     
  Lines        9428     9207     -221     
==========================================
- Hits         6453     6333     -120     
+ Misses       2277     2191      -86     
+ Partials      698      683      -15

[prestonvanloon]

Looks like this test can pass if err is nil