fix: Fix the crash problem of postbox

[QZero233]

Detailed bug reproduce see Creators-of-Create#9785
Below is a copy of the original issue (Written by @Sukiet):

Context

Full sequence

1. A chute inserts items into a white postbox.
2. The inventory-change callback notifies neighbouring blocks.
3. A redstone comparator next to the postbox asks for the analog signal strength.
4. Create’s ItemHelper.calcRedstoneFromInventory() calls TransferUtil.getTransaction() to access the item cache.
5. This runs inside a Transaction.close() callback; Fabric API forbids getCurrentUnsafe() at that moment and throws IllegalStateException.
6. The exception is caught as a “Ticking block entity” error and the server is killed.

How to reproduce

1. Place a white postbox.
2. Put a redstone comparator against the postbox so it reads the fill level.
3. Insert items through Create logistics (chutes, funnels, etc.).
4. Wait for item transfer -> instant crash.

Crash Report

https://mclo.gs/TXsULuX

[TesseractGitHub]

This also fixes the same problem where a comparator being placed next to a frogport will crash the game when a package is received! Fix works well 👍