Issue 663 — platformLinkOp(): 2× E_WARNING "Trying to access array offset on null" on EVERY successful removePlatformFromTestPlan

Issue: #663 Branch: fix/issue-663 · Commit: e3d1c1eea (fix, +5/−2) + 09248397d (regression suite) Status: FIXED & VERIFIED (2026-08-24)

Symptom

Every SUCCESSFUL tl.removePlatformFromTestPlan call where the platform has ZERO linked test case versions (the normal case) returns the correct payload ({operation: unlink, msg: 'unlink done', linkStatus: true}) but ALSO writes 2 × E_WARNING rows into the Event Viewer (events table):

mysql> SELECT id, log_level, description FROM events\G
     log_level: 2
  description: E_WARNING
Trying to access array offset on null - in .../lib/api/xmlrpc/v1/xmlrpc.class.php - Line 7008
     log_level: 2
  description: E_WARNING
Trying to access array offset on null - in .../lib/api/xmlrpc/v1/xmlrpc.class.php - Line 7008

Two rows because line 7008 performs two chained offset reads ($hits[$platform['id']] then ['qty']) on a NULL value.

Repro measured live (fresh DB, events table truncated to 0 first): admin devKey, fixtures built through the API itself (createTestProject, createTestPlan, createPlatform, addPlatformToTestPlan), then removePlatformFromTestPlan. Response correct, events table gained exactly 2 E_WARNING rows at Line 7008.

Root cause chain

1. lib/api/xmlrpc/v1/xmlrpc.class.php:6841 — removePlatformFromTestPlan() delegates to private platformLinkOp() (:6958) with $op='unlink'.
2. :7007 — unlink branch calls $hits = $this->tplanMgr->countLinkedTCVersionsByPlatform($testPlanID,(array)$platform['id']);
3. lib/functions/testplan.class.php:3521-3533 — that method runs a GROUP BY platform_id query and ends with return $this->db->fetchRowsIntoMap($sql,'platform_id');. When NO row matches (platform linked to the plan but zero testplan_tcversions rows use it), fetchRowsIntoMap() returns null, never an empty array.
4. :7008 — if($hits[$platform['id']]['qty'] == 0) reads offsets off null ⇒ E_WARNING ×2. The expression still evaluates true (null == 0), so the unlink proceeded correctly — damage was pure event-log pollution.

Blast radius

Exactly ONE unguarded consumer repo-wide:

Consumer	Guard
lib/api/xmlrpc/v1/xmlrpc.class.php:7007-7014	none (bug)
lib/platforms/platformsAssign.php:39-41	isset($qtyByPlatform[0]['qty']) ? … : 0
api/platforms/index.php:550-551	isset(...) && intval(...) > 0
api/platforms/index.php:635-636	same isset pattern

The GUI/BFF layers were never affected; only the XMLRPC API call site lacked the convention. The error branch at :7014 re-reads the qty for its message, but only executes when qty > 0 ($hits non-null there) — normalizing once covers both reads.

Approach — normalize to $hitsQty via isset() (minimal, matches existing convention)

At xmlrpc.class.php:7007-7015:

$hits = $this->tplanMgr->countLinkedTCVersionsByPlatform( $testPlanID,( array ) $platform['id'] );
// fetchRowsIntoMap() returns null when the GROUP BY matches no row
// (platform linked but zero TC versions use it)
$hitsQty = isset($hits[$platform['id']]['qty']) ? intval($hits[$platform['id']]['qty']) : 0;
if($hitsQty == 0) { ... 'unlink done' ... }
else { ... sprintf(PLATFORM_REMOVETC_NEEDED_BEFORE_UNLINK_STR, $platName, $hitsQty); }

Rejected alternatives:

• changing countLinkedTCVersionsByPlatform() to return [] instead of null — alters a public method consumed by three working callers (return-type change risk for zero benefit);
• guarding inside fetchRowsIntoMap() — touches the shared DB layer far beyond this bug's blast radius;
• deleting the count check — would remove the PLATFORM_REMOVETC_NEEDED_ BEFORE_UNLINK contract shared with the GUI behaviour.

Verification (Suite 663 — 7/7 PASS, see tmp/TLU_Test_Cases.md)

Regression matrix executed live against http://localhost:8082 with events table truncated before every case:

#	Scenario	Result
R1	unlink linked platform, ZERO TC versions (primary bug case)	{unlink done} correct, ZERO new events (was: +2 E_WARNING @7008)
R2	unlink when not linked	{nothing to do}, no new events
R3	unlink blocked by 1 linked TC version	code 12001, message correctly says "used by 1 test case(s)", no new events
R4	unknown platform name	code 235 unchanged, no new events
R5	link op after fix	{link done}, no new events
R6	sibling consumers untouched	platformsAssign.php / api/platforms/index.php already guarded, untouched
—	syntax gate	php -l clean

Event Viewer watermark stayed at 0 across the entire post-fix matrix.

Side discovery (already tracked, not touched here)

Building case 3's fixture through tl.createTestCase + tl.addTestCaseToTestPlan reproduced open issue #661: documented step key expectedresults triggers E_WARNING "Undefined array key "expected_results"" at testcase.class.php:803 and links the version with platform_id=0. No duplicate filed.