Leaflet map formatter throws "Undefined array key" warnings for minZoom/maxZoom

Leaflet map formatter throws "Undefined array key" warnings for minZoom/maxZoom on event pages

Problem/Motivation

Event nodes (and any other content using the Leaflet map formatter) throw PHP warnings on render:

Warning: Undefined array key "minZoom" in Drupal\leaflet\Plugin\Field\FieldFormatter\LeafletDefaultFormatter->setExistingZoomSettings() (line 530 of modules/contrib/leaflet/src/Plugin/Field/FieldFormatter/LeafletDefaultFormatter.php).
Warning: Undefined array key "maxZoom" in Drupal\leaflet\Plugin\Field\FieldFormatter\LeafletDefaultFormatter->setExistingZoomSettings() (line 531 of modules/contrib/leaflet/src/Plugin/Field/FieldFormatter/LeafletDefaultFormatter.php).

setExistingZoomSettings() computes zoom bounds with:

$settings['map_position']['minZoom'] = (int) $settings['minZoom'] ?? 3;
$settings['map_position']['maxZoom'] = (int) $settings['maxZoom'] ?? 16;

(int) binds tighter than ??, so this actually evaluates as ((int) $settings['minZoom']) ?? 3. When a field formatter's settings define zoom but not minZoom/maxZoom (a perfectly valid, common configuration — e.g. this site's Event field_map_location display only sets zoom: 12), PHP throws the "Undefined array key" warning on the array access, then casts the resulting NULL to 0 — which is never falsy enough for ?? to fall through to its fallback.

So this bug is two problems in one: a noisy warning on every render, and a silent functional regression where minZoom/maxZoom resolve to 0 instead of the intended defaults (3/16).

Steps to reproduce

1. Configure a Leaflet-formatted field's display settings with zoom set, but leave minZoom/maxZoom unset (e.g. save a field formatter config that predates those settings being introduced, or any formatter settings array where only zoom was ever populated).
2. View any entity that renders that field (e.g. an Event node using the default view mode's field_map_location formatter).
3. Observe the two "Undefined array key" warnings, and note that map_position.minZoom/map_position.maxZoom are 0 rather than the documented defaults of 3 and 16.

Minimal reproduction outside Drupal:

$settings = ['zoom' => 12];
$minZoom = (int) $settings['minZoom'] ?? 3; // warning; $minZoom === 0, not 3

Proposed resolution

Parenthesize the null-coalesce so it runs before the cast, per PHP operator precedence:

$settings['map_position']['zoom'] = (int) ($settings['zoom'] ?? 10);
$settings['map_position']['minZoom'] = (int) ($settings['minZoom'] ?? 3);
$settings['map_position']['maxZoom'] = (int) ($settings['maxZoom'] ?? 16);

This removes the warning and restores the intended fallback behavior. Applied locally as patches/leaflet_fix_undefined_zoom_settings.patch, registered against drupal/leaflet in composer.json.

Remaining tasks

• Commit the patch file and composer.json change.
• Confirm composer install re-applies the patch cleanly in CI/build.
• Deploy and verify the warnings are gone on the Event default view mode in a live environment.
• Optionally report/submit this fix upstream to the drupal/leaflet project on drupal.org so it doesn't need to be carried as a local patch indefinitely.

User interface changes

None. The PHP warnings were not user-facing on this site (system.logging:error_level is set to hide), so no visible UI change — this is a backend correctness/log-noise fix. Sites with error_level set to display errors on screen would no longer see the warning text appear on map-formatted field renders.

API changes

None. The fix only corrects the internal computation inside setExistingZoomSettings(); no public method signatures, hooks, or plugin interfaces are affected.

Data model changes

None. No field storage, configuration schema, or entity structure is altered. Existing field formatter settings (with or without minZoom/maxZoom keys) continue to be read as-is; only the resolved in-memory default now matches the documented fallback (3/16 instead of 0).