Update PostingsList's chunkSize only when err == nil

[abhinavdangeti]

Possibly related to: blevesearch/bleve#1811

[Thejas-bhat]

A doubt here, from the code:

	case chunkMode == 1026:
		// improve upon the ideas tested in chunkMode 1025
		// the observation that the fewest number of dense chunks is the most
		// desirable layout, given the built-in assumptions of chunking
		// (that we want to put an upper-bound on the number of items you must
		//  walk over without skipping, currently tuned to 1024)
		//
		// 1.  compute the number of chunks needed (max 1024/chunk)
		// 2.  convert to chunkSize, dividing into maxDocs
		numChunks := (cardinality / 1024) + 1
		chunkSize := maxDocs / numChunks

		return chunkSize, nil

it seems like we could potentially return a zero chunkSize if the passed value of d.sb.numDocs is zero. Do we handle that part as well?

[abhinavdangeti]

Ya good point.