damage_sensor has an invalid child error with more than one child in an array

Partner Rank: 1

Partner Team Reporting: Spark Squared

Verification builds: 1.13.0.2

Summary: 

damage_sensor has an invalid child error with more than one child in an array

Impact:

In the Lucky Blocks: Classic map, lucky blocks are able to be damaged rather than punched to be destroyed, which hinders the gameplay.

Repro Steps:

1. Open the Lucky Blocks map by Spark Squared from the Marketplace
2. Notice the content log error
3. Also, punch a lucky block
4. Notice they get damaged rather than destroyed

Observed Results:

There is an error which states:

18:52:02[Json][error]-Lucky Blocks Classic | actor_definitions | C:/Users/dest/AppData/Local/Packages/Microsoft.MinecraftUWP_8wekyb3d8bbwe/LocalState/games/com.mojang/minecraftWorlds/LuckyBlock/behavior_packs/lucky__bp | spark:lucky_block | minecraft:entity | component_groups | lucky:random_all | minecraft:damage_sensor |  | child '' not valid here.

Lucky blocks do not get destroyed after punching them 

Expected Results:

There is no content log error and the lucky blocks are not damageable

Regression Builds:

1.12.0.27

Notes:

This error is similar to MCM-702, which was fixed, however, this error seems to appear when there are multiple damage sensors in the damage_sensor array. In other maps which had problems resulting from 702, there was only one `{ "cause" : "all", "deals_damage" : false }` damage sensor, while in Lucky Blocks there is another trigger which seems to cause this error to re-surface.