Script API: effectAdd signals sometimes do not fire when minecraft:instant_damage is applied

When the minecraft:instant_damage effect is applied to entities during the entity system update tick phase, callbacks subscribed to world.beforeEvents.effectAdd and world.afterEvents.effectAdd will not get notified.

Steps to reproduce

1. Download the pack attached to this bug report.

2. Add the pack to a new world.

3. Spawn some mobs and apply the minecraft:instant_damage effect to them in various ways.

The pack attached to this bug report will send a message in the world chat when the effectAdd signals fire. The message will indicate the type of event and some info.

Expected outcome

Both effectAdd signals will always fire when minecraft:instant_damage is applied to an entity, regardless of when or how the effect is applied.

Actual outcome

The effectAdd signals may or may not fire depending on how minecraft:instant_damage was applied.

The effectAdd signals will not fire when:

• a tipped instant damage arrow hits an entity

• a splash instant damage potion lands near an entity

• a lingering potion AOE cloud applies instant damage to an entity

• a command block minecart on activated activator rail runs /effect, applying instant damage to an entity

The effectAdd signals will fire when:

• a player runs /effect in chat, applying instant damage to an entity

• a command block runs /effect, applying instant damage to an entity