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Overview

Players with a disk-saved clipboard containing entities get a StringIndexOutOfBoundsException on every join, because the stored entity NBT uses the vanilla lowercase id tag that FAWE doesn't read. This PR makes FAWE accept both Id and id and handle a missing id safely.

Fixes #2494

Description

Entity NBT stored in a disk clipboard can carry the vanilla lowercase id tag instead of FAWE's internal Id. BaseEntity(CompoundTag) only read Id and got an empty string. EntityTypes.convertEntityId then threw a StringIndexOutOfBoundsException on charAt(0), so entity loading for the clipboard was aborted every time the player joined:

java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
    at com.sk89q.worldedit.world.entity.EntityTypes.convertEntityId(EntityTypes.java:558)
    at com.sk89q.worldedit.world.entity.EntityTypes.parse(EntityTypes.java:567)
    at com.sk89q.worldedit.entity.BaseEntity.<init>(BaseEntity.java:126)
    at com.fastasyncworldedit.core.extent.clipboard.DiskOptimizedClipboard.loadNBTFromFileFooter(DiskOptimiz
     edClipboard.java:275)

Submitter Checklist

• Make sure you are opening from a topic branch (/feature/fix/docs/ branch (right side)) and not your main branch.
• Ensure that the pull request title represents the desired changelog entry.
• New public fields and methods are annotated with @since TODO.
• I read and followed the contribution guidelines.

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[SirYwell]

Why can this be the case?

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Why can this be the case?

CompoundTag#getString returns "" for a missing key. That's what caused #2494: there was only id, so getString("Id") returned "" and charAt(0) threw. The id fallback covers that case, but a tag with neither key would still crash. Other callers of parse (e.g. MutableEntityChange) could hit it too. It's just a defensive check, so I can drop it if you prefer.