[1.8] Assert error when trying to open a world.

Verification builds: 1.8.0.4_beta-26 (release/dev build), 1.7.0_invisMobFix** (release/dev build)

Summary: Assert error when trying to open a world.

Impact: It doesn't work to open the world.

Repro Steps:

1. Download the 1.7.0_invisMobFix (release/dev build) build or 1.8.0.4_beta-26 (release/dev build).
2. Please go to the PixelHeads Slack channel or Auger to see which world this affects. It's our latest submitted map.
3. Import the world.
4. Try to open the world.

Observed Results:

I get the following error. (See attachment for more info.)

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Assert Failure - ctrl+C to copy this message to the clipboard!
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Assertion failed: must have at least 1 recieve.
Condition is false: !trade.mReceive.empty()
Function: parseAllTradeJson in f:\darwinwork\87\s\handheld\src\common\world\item\trading\tradetables.cpp @ 174

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OK
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Expected Results:

It should be possible to open the world. It was never an issue on the 1.6.x or 1.7.0.9_beta-25

Screenshots/Videos attached: Yes

Regression Build

v1.6.1 (publish build), 1.7.0.9_beta-25 (publish build)

Notes:

**I think I have found the files which are causing the errors. But I have no idea what is causing it to happen.

• /behaviors_packs/BP_XX/trading/pop_star.json
• /resource_packs/RP_XX/materials/entity.material