fabric 1.19.4, 0.14.21, e2j 1.10.1
It spams it like hell, creates lags especially with worldgen:

[16:20:21] [Worker-Main-26/WARN]: Failed to create mob
java.lang.NullPointerException: Cannot invoke "net.minecraft.class_4980.method_26311()" because "this.field_23230" is null
at net.minecraft.class_1452.method_6725(class_1452.java:176) ~[server-intermediary.jar:?]
at net.minecraft.class_1452.method_5642(class_1452.java:84) ~[server-intermediary.jar:?]
at net.minecraft.class_1309.method_49476(class_1309.java:3542) ~[server-intermediary.jar:?]
at net.minecraft.class_1309.handler$zii000$beaconoverhaul$setDefaultStepHeight(class_1309.java:7685) ~[server-intermediary.jar:?]
at net.minecraft.class_1309.(class_1309.java:258) ~[server-intermediary.jar:?]
at net.minecraft.class_1308.(class_1308.java:134) ~[server-intermediary.jar:?]
at net.minecraft.class_1314.(class_1314.java:14) ~[server-intermediary.jar:?]
at net.minecraft.class_1296.(class_1296.java:29) ~[server-intermediary.jar:?]
at net.minecraft.class_1429.(class_1429.java:42) ~[server-intermediary.jar:?]
at net.minecraft.class_1452.(class_1452.java:58) ~[server-intermediary.jar:?]
at slexom.earthtojava.entity.base.E2JBasePigEntity.(E2JBasePigEntity.java:20) ~[earth2java-fabric-1.10.1+1.19.4.jar:?]
at net.minecraft.class_1299.method_5883(class_1299.java:544) ~[server-intermediary.jar:?]
at net.minecraft.class_1948.method_8661(class_1948.java:518) ~[server-intermediary.jar:?]
at net.minecraft.class_3754.method_12107(class_3754.java:455) ~[server-intermediary.jar:?]
at net.minecraft.class_2806.method_17033(class_2806.java:175) ~[server-intermediary.jar:?]
at net.minecraft.class_2806$class_3768.doWork(class_2806.java:342) ~[server-intermediary.jar:?]
at net.minecraft.class_2806.method_12154(class_2806.java:293) ~[server-intermediary.jar:?]
at net.minecraft.class_3898.method_17225(class_3898.java:692) ~[server-intermediary.jar:?]
at com.mojang.datafixers.util.Either$Left.map(Either.java:38) ~[datafixerupper-6.0.6.jar:?]
at net.minecraft.class_3898.method_17224(class_3898.java:686) ~[server-intermediary.jar:?]
at java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1150) ~[?:?]
at java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:482) ~[?:?]
at net.minecraft.class_3900.method_17634(class_3900.java:62) ~[server-intermediary.jar:?]
at net.minecraft.class_3846.method_16907(class_3846.java:91) ~[server-intermediary.jar:?]
at net.minecraft.class_3846.method_16900(class_3846.java:146) ~[server-intermediary.jar:?]
at net.minecraft.class_3846.run(class_3846.java:102) ~[server-intermediary.jar:?]
at java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1395) ~[?:?]
at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:373) ~[?:?]
at java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1182) ~[?:?]
at java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1655) ~[?:?]
at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1622) ~[?:?]
at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:165) ~[?:?]

Note: it also sometimes does that with Beacon Overhaul 1.19.4, 1.7.6, but it mostly seems to happen with e2j

Edit: Any pig (basic minecraft or e2j) won't spawn. Eggs don't work and /summon doesn't work. Naturally they don't occur.