NullPointer Fix for Mio

This mod safely modifies the core read method of Minecraft network packets. Whenever any mod attempts to write null into a packet, the method automatically replaces null with an empty CompoundTag at the return stage, ensuring that any subsequent NBT operations (such as getString, getInt, etc.) will not throw a null pointer exception.

Notes • This is a crash guard, not a data fix: a skipped feature may stop working temporarily (for example, one dropped item is discarded or one block entity stops ticking), but the server/client stays alive. • Only null-pointer exceptions are suppressed; other errors still produce a normal crash report. 

[NullPointer Fix for Mio  — How to enable the extra protections]

Both options are OFF by default. Only enable them if your crash log contains:
Slot.getItem / Inventory.setItem / Inventory.add / NonNullList

Add these JVM arguments:
-Dnullpointerfix.sanitizeSlots=true
-Dnullpointerfix.sanitizeInventory=true

Client (close the game first):
• CurseForge: Settings → Game Specific → Minecraft → Java Arguments, append at the end
• Prism: right-click instance → Edit → Settings → Java → JVM arguments, append at the end
• HMCL: Version Settings → Advanced Settings → JVM Arguments, append at the end
• PCL2: Settings → Launch Settings → Advanced → JVM Arguments, append at the end
• Official Launcher: Installations → Edit → More Options → JVM arguments, append at the end

Note: put them in the "JVM / Java arguments" field, NOT in "Game arguments".

Server (Forge 1.19/1.20, NeoForge 1.21):
Open user_jvm_args.txt in the server folder and add one per line:
-Dnullpointerfix.sanitizeSlots=true
-Dnullpointerfix.sanitizeInventory=true
Save and restart.
If your start script does not read that file, put the arguments between java and -jar.

How to verify:
After launch, logs/latest.log should contain:
[NPE-Fix] NullPointerFixForMio active (... slots=true, inventory=true ...)

How to disable:
Remove the arguments and restart the game/server.

Notes:
• Client crash → add on the client. Server crash → add on the server. One side does not affect the other.
• If items disappear, storage terminals misbehave, or inventories get out of sync, remove the arguments first.
• All other protections are enabled by default. These two are optional.

This mod safely modifies the core read method of Minecraft network packets. Whenever any mod attempts to write null into a packet, the method automatically replaces null with an empty CompoundTag at the return stage, ensuring that any subsequent NBT operations (such as getString, getInt, etc.) will not throw a null pointer exception.

Notes • This is a crash guard, not a data fix: a skipped feature may stop working temporarily (for example, one dropped item is discarded or one block entity stops ticking), but the server/client stays alive. • Only null-pointer exceptions are suppressed; other errors still produce a normal crash report.

[NullPointer Fix for Mio — How to enable the extra protections]

Both options are OFF by default. Only enable them if your crash log contains: Slot.getItem / Inventory.setItem / Inventory.add / NonNullList

Add these JVM arguments: -Dnullpointerfix.sanitizeSlots=true -Dnullpointerfix.sanitizeInventory=true

Client (close the game first): • CurseForge: Settings → Game Specific → Minecraft → Java Arguments, append at the end • Prism: right-click instance → Edit → Settings → Java → JVM arguments, append at the end • HMCL: Version Settings → Advanced Settings → JVM Arguments, append at the end • PCL2: Settings → Launch Settings → Advanced → JVM Arguments, append at the end • Official Launcher: Installations → Edit → More Options → JVM arguments, append at the end

Note: put them in the "JVM / Java arguments" field, NOT in "Game arguments".

Server (Forge 1.19/1.20, NeoForge 1.21): Open user_jvm_args.txt in the server folder and add one per line: -Dnullpointerfix.sanitizeSlots=true -Dnullpointerfix.sanitizeInventory=true Save and restart. If your start script does not read that file, put the arguments between java and -jar.

How to verify: After launch, logs/latest.log should contain: [NPE-Fix] NullPointerFixForMio active (... slots=true, inventory=true ...)

How to disable: Remove the arguments and restart the game/server.

Notes: • Client crash → add on the client. Server crash → add on the server. One side does not affect the other. • If items disappear, storage terminals misbehave, or inventories get out of sync, remove the arguments first. • All other protections are enabled by default. These two are optional.