Add safety guards in Generate item flow for invalid references and non-existent classes

[bygadd]

Summary

The Generate item massive action throws fatal errors on GLPI 11 / PHP 8.3 under two scenarios that have become common after the GLPI 10 → 11 migration:

1. Invalid item references in PluginOrderReference::getReferenceItemID() — getItemForItemtype() returns false in HTTP context for some dynamically-generated classes (notably Glpi\CustomAsset\* in GLPI 11), causing Call to a member function getFromDB() on false. Existing references migrated from older itemtypes may also have templates_id = 0, which makes getFromDB() fail silently and downstream getField() calls operate on a half-initialised object.

2. Non-existent classes in PluginOrderLink::generateItem() — Toolbox::hasTrait() internally calls class_uses(). On PHP 8.3 with the Safe library wrapper, class_uses() on a non-existent class throws Safe\Exceptions\SplException instead of emitting a warning. This is triggered by stale itemtype values in glpi_plugin_order_orders_items that reference classes from uninstalled plugins (e.g. PluginGenericobjectOther after migrating to native custom assets via the GenericObject 3.0.0 EOL migration tool).

Implementation

Both call sites are now guarded:

• inc/reference.class.php — bail out early with return 0 when the item cannot be instantiated or templates_id is empty.
• inc/link.class.php — prefix both Toolbox::hasTrait() calls with class_exists() so non-existent classes are skipped cleanly, both in the iteration loop (where $row['assignableitem'] is set) and in the final TemplateRenderer::display() call.

The changes are defensive and minimal — they preserve all existing behaviour for valid native itemtypes, and only short-circuit when the underlying data cannot be resolved to a working class.

Testing

Tested on GLPI 11.0.7, PHP 8.3, Order plugin 2.12.6:

Scenario	Result
Order with valid native itemtypes (Computer, Monitor, etc.) — unchanged behaviour	✅
Order containing custom asset references (Glpi\CustomAsset\otherAsset) — form now renders fully and submits	✅
Order containing stale itemtypes from uninstalled plugins (PluginGenericobjectOther) — items skipped without fatal error, remaining items render	✅
Generate item massive action end-to-end (form → submit → items created)	✅

Tested on a production instance with ~21,000 order line items and ~1,300 references, including a mix of native itemtypes, custom asset references, and stale references from a deinstalled plugin.

Checklist

• I have performed a self-review of my code.
• I have added tests (when available) that prove my fix is effective or that my feature works.
• I have updated the CHANGELOG with a short functional description of the fix or new feature.
• This change requires a documentation update.

[bygadd]

Related: opened pluginsGLPI/room#64 today documenting similar GLPI 11 compatibility issues in the room plugin — including null-safety patterns analogous to the ones in this PR (guard before object instantiation, guard before trait checks).

The room patch set is in production use on the same instance where this PR's guards were developed (GLPI 11.0.7, ~700K warnings/day → 0).