Importing a Mantis bug-tracker XML (modern BFF api/reqfromissues — the #1503 screen — or the legacy reqCreateFromIssueMantisXML.php / reqImport.php paths) whose issue docid hits an existing requirement that has no req_versions child row logs a spurious warning into the Event Viewer / events table on every import:

E_WARNING
Trying to access array offset on null - in .../lib/functions/requirement_mgr.class.php - Line 1624

(observed in-prod as events 34/35 while testing #1503). The import itself still completes — the warning is emitted by the frozen-requirement check dereferencing a null returned by get_last_child_info().

• App http://localhost:8082 (PHP 8.3), admin/admin; MariaDB testlink.
• Fixture: testproject id=1, req spec id=2 (req_specs_revisions id=3), and a version-less requirement id=4 under spec 2 with req_doc_id = 'Mantis Task ID:20' and NO req_versions child row (the half-created state a legacy import fatal can leave behind).
• POST /api/reqfromissues/?action=import&req_spec_id=2 with a Mantis XML whose <issue><id>20</id> maps to docid 'Mantis Task ID:20' (multipart field uploadedFile, header X-Requested-With: XMLHttpRequest).

Chain (each hop file:line):

1. api/reqfromissues/index.php:388-389 and legacy reqCreateFromIssueMantisXML.php:205 enqueue one requirement per <issue> into requirement_mgr::createFromMap() (lib/functions/requirement_mgr.class.php:1480) with docid='Mantis Task ID:<id>'.
2. createFromMap() finds an existing hit inside the spec branch via getByAttribute(target, tproject_id, parent_id, ['output'=>'id']) (line 1580).
3. On a hit, line 1620 requests the last version: get_last_child_info($reqID, ['child_type'=>'version', 'output'=>' CHILD.is_open, CHILD.id ']) (options from line 1517).
4. get_last_child_info() (lines 2896-2945) runs SELECT COALESCE(MAX(version),-1) FROM req_versions CHILD, nodes_hierarchy NH WHERE NH.id = CHILD.id AND NH.parent_id = {id}. A requirement owning no req_versions child gives MAX = -1; the if ($max_verbose >= 0) branch (line 2919) is skipped and the function returns null.
5. Pre-fix line 1624 read $last_version['is_open'] == 1 unconditionally. PHP 8 emits E_WARNING Trying to access array offset on null. Because null == 1 is false, the expression fell through to the skipFrozenReq default (true, line 1530) → the requirement is skipped as "is FROZEN" — the warning is pure noise (Event Viewer pollution), no flow/correctness impact.

Blast radius: createFromMap() is the single choke-point for every requirement import surface (BFF reqfromissues + reqimport, legacy reqImport CSV/DocBook/ XML) — any import hitting an existing docid whose requirement owns no req_versions child triggers the warning.

lib/functions/requirement_mgr.class.php:1624 — guard the dereference:

if( (is_array($last_version) && isset($last_version['is_open']) && $last_version['is_open'] == 1)
    || !$my['options']['skipFrozenReq']) {

A null / non-array $last_version now short-circuits to the skip path (under the default skipFrozenReq = true, line 1530) with zero warnings; a real open-version hit keeps its exact previous semantics.

events table after all verification (post-fix imports added nothing): id=1 AUDIT login succeeded (1789449314), id=2 WARNING E_WARNING ... Line 1624 (1789449341 — the deliberately captured PRE-FIX A/B repro).

Regression — Issue #1505 in tmp/TLU_Test_Cases.md — 6/6 PASS (skip behavior, events clean, repeat import, lint + guard presence, A/B pre/post, final Event Viewer check).

• lib/functions/requirement_mgr.class.php (guard at line 1624 — landed in commit 681d39dbc with Fixes #1505)
• tmp/TLU_Test_Cases.md (regression suite 1505 appended)
• this doc + docs/screenshots/issue-1505-events-table-ewarning.png + wiki mirror

Refs #1505.