In Performance Digests the description may be inconsistent

[niklas88]

E.g for a query:

PREFIX wdt: <http://www.wikidata.org/prop/direct/>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT ?y ?label WHERE {
  wd:Q60025 ?y ?label .
  FILTER langMatches(lang(?label), "en") .
}

We may get the digest

Join on ?label
result_size: 10 x 2
total_time: 0.00 ms
operation_time: 0.00 ms
cached: true
    OriginalTime: 0.00 ms

  IndexScan ?label <QLever-internal-function/langtag> <QLever-internal-function/@en>
  result_size: 46,350,904 x 1
  total_time: 0.00 ms
  operation_time: 0.00 ms
  cached: true
      OriginalTime: 547.00 ms

  IndexScan <http://www.wikidata.org/entity/Q60025> ?y ?qleverui_entity
  result_size: 1,009 x 2
  total_time: 0.00 ms
  operation_time: 0.00 ms
  cached: true
      OriginalTime: 52.00 ms

which has the inconsistent column names in the second IndexScan because the description is taken from the cache.