Fix buildLimit() silently dropping OFFSET 0

[darkspock]

Summary

AbstractDQLQueryBuilder::buildLimit() uses !empty($offset) to decide whether to append the OFFSET clause. Since empty(0) returns true in PHP, an explicitly set OFFSET 0 is silently dropped from the generated SQL.

While OFFSET 0 has no semantic effect on query results, this is inconsistent: a value explicitly set by the caller should be reflected in the output. It can also cause confusion when debugging generated SQL.

Fix

Replace !empty($offset) with $offset !== null, which correctly distinguishes "no offset set" (null) from "offset is zero" (0).

Before

if (!empty($offset)) {

After

if ($offset !== null) {

Risk

Very low — the only change is that OFFSET 0 now appears in the SQL when explicitly set. This has no effect on query results.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.62%. Comparing base (b9d25ca) to head (d7a6381).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1173      +/-   ##
============================================
- Coverage     98.62%   98.62%   -0.01%     
  Complexity     1645     1645              
============================================
  Files           120      120              
  Lines          4292     4284       -8     
============================================
- Hits           4233     4225       -8     
  Misses           59       59              

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[vjik]

"no offset set" (null) and "offset is zero" (0) gives equal result in SQL. I agree with @Tigrov and suggest don't change it.

But it will be useful to add an explanation to the description of methods that set offset.