Fix bug for materialized join results with lazy input with local vocabs

[joka921]

This fixes a subtle bug which led to a segmentation fault in the following scenario:

1. The result of a join is fully materialized, but at least one of its inputs is lazy
2. The blocks of the unique input contain local vocabs with unique entries (not shared between the blocks)
3. There is at least one block in the lazy input that has no matching row in the other input, and therefore its local vocab is not used
4. There is at least one block before the block from item 3 that is needed (including its local vocab)

Previously, the local vocabs from all blocks that fulfill item 3 were not part of the input and caused segfaults, when the corresponding local vocab pointer was dereferenced.

Fixes #1679

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.86%. Comparing base (27f4799) to head (c6f3d45).
Report is 4 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1684      +/-   ##
==========================================
+ Coverage   89.76%   89.86%   +0.10%     
==========================================
  Files         389      389              
  Lines       37149    37190      +41     
  Branches     4194     4197       +3     
==========================================
+ Hits        33346    33422      +76     
+ Misses       2502     2472      -30     
+ Partials     1301     1296       -5     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[hannahbast]

Thanks a lot for the fix! Slight improvement of a comment

[sparql-conformance]

Conformance check passed ✅

No test result changes.

Details: https://qlever.cs.uni-freiburg.de/sparql-conformance-ui?cur=c6f3d452c0ec3aa2d58d1d5f8eb6117caef37ec4&prev=44c2b4fb8061abd35bd2653010c10f612d64a94b

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud