---- Minecraft Crash Report ----
// Hi. I'm Minecraft, and I'm a crashaholic.

Time: 04/04/20 17:06
Description: Exception in server tick loop

java.lang.ClassCastException: enemeez.simplefarming.block.growable.FruitLeavesBlock cannot be cast to net.minecraft.block.LeavesBlock
at net.olafkeijsers.fastleafdecay.FldScheduler.tick(FldScheduler.java:55) ~[?:v20] {re:classloading}
at net.olafkeijsers.fastleafdecay.FastLeafDecay$$Lambda$2397/1496057473.accept(Unknown Source) ~[?:?] {}
at net.minecraftforge.eventbus.EventBus.doCastFilter(EventBus.java:212) ~[eventbus-2.0.0-milestone.1-service.jar:?] {}
at net.minecraftforge.eventbus.EventBus.lambda$addListener$11(EventBus.java:204) ~[eventbus-2.0.0-milestone.1-service.jar:?] {}
at net.minecraftforge.eventbus.EventBus$$Lambda$2056/906824826.invoke(Unknown Source) ~[?:?] {}
at net.minecraftforge.eventbus.EventBus.post(EventBus.java:258) ~[eventbus-2.0.0-milestone.1-service.jar:?] {}
at net.minecraftforge.fml.hooks.BasicEventHooks.onPostServerTick(BasicEventHooks.java:119) ~[?:?] {re:classloading}
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:823) ~[?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:114) ~[?:?] {re:classloading,pl:runtimedistcleaner:A}
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:635) [?:?] {re:classloading,pl:accesstransformer:B}
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_51] {}

A detailed walkthrough of the error, its code path and all known details is as follows:

-- System Details --
Details:
Minecraft Version: 1.15.2
Minecraft Version ID: 1.15.2
Operating System: Windows 10 (amd64) version 10.0
Java Version: 1.8.0_51, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 2838176008 bytes (2706 MB) / 4294967296 bytes (4096 MB) up to 4294967296 bytes (4096 MB)
CPUs: 4
JVM Flags: 9 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -Xmx4G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
ModLauncher: 5.0.0-milestone.4+67+b1a340b
ModLauncher launch target: fmlclient
ModLauncher naming: srg
ModLauncher services:
/eventbus-2.0.0-milestone.1-service.jar eventbus PLUGINSERVICE
/forge-1.15.2-31.1.0.jar object_holder_definalize PLUGINSERVICE
/forge-1.15.2-31.1.0.jar runtime_enum_extender PLUGINSERVICE
/accesstransformers-2.0.0-milestone.1-shadowed.jar accesstransformer PLUGINSERVICE
/forge-1.15.2-31.1.0.jar capability_inject_definalize PLUGINSERVICE
/forge-1.15.2-31.1.0.jar runtimedistcleaner PLUGINSERVICE
/forge-1.15.2-31.1.0.jar fml TRANSFORMATIONSERVICE
/MixinBootstrap-1.0.2.jar mixinbootstrap TRANSFORMATIONSERVICE
/MixinBootstrap-1.0.2.jar mixin PLUGINSERVICE
/MixinBootstrap-1.0.2.jar mixinbootstrap PLUGINSERVICE
FML: 31.1
Forge: net.minecraftforge:31.1.0
FML Language Providers:
[email protected]
minecraft@1
Mod List:
forge-1.15.2-31.1.0-client.jar Minecraft {[email protected] DONE}
mcw-bridges-1.0.4fix-mc1.15.2.jar Macaw's Bridges {[email protected] DONE}
QuarkOddities-1.15.2.jar Quark Oddities {[email protected] DONE}
AmbientSounds_v3.0.19_mc1.15.2.jar Ambient Sounds {[email protected] DONE}
Blur-1.1.0-1.jar Blur {[email protected] DONE}
simplylight-1.15.2-0.9.0.jar Simply Light {[email protected] DONE}
simplefarming-1.15.2-1.2.7.jar Simple Farming {[email protected] DONE}
mcw-windows-1.0.0-mc1.15.1_1.15.2.jar Macaw's Windows {[email protected] DONE}
Waystones_1.15.2-6.0.1.jar Waystones {[email protected] DONE}
JRFTL+[1.15.2]-1.1.jar JRFTL {[email protected] DONE}
journeymap-1.15.2-5.7.0beta1.jar Journeymap {[email protected] DONE}
CookingForBlockheads_1.15.2-8.0.1.jar Cooking for Blockheads {[email protected] DONE}
autumnity-1.1.0-1.15.2.jar Autumnity {[email protected] DONE}
AutoRegLib-1.5-40.jar AutoRegLib {[email protected] DONE}
Ore-Excavation-Mod-1.15.2.jar Ore Excavation {oreexcavation@NONE DONE}
NaturesCompass-1.15.2-1.8.5.jar Nature's Compass {[email protected] DONE}
backpacked-1.4.1-1.15.2.jar Backpacked {[email protected] DONE}
mcw-roofs-1.0.2-mc1.15.2_1.15.1.jar Macaw's Roofs {[email protected] DONE}
AppleSkin-mc1.15.2-forge-1.0.13.jar AppleSkin {[email protected] DONE}
carpetstairsmod-mc1.15-v1.4.1.jar Carpet Stairs Mod {[email protected] DONE}
betterbedrockgenerator-1.15.2-0.0.6.jar Better Bedrock Generator {[email protected] DONE}
swampexpansion-1.15.2-1.5.jar Swamp Expansion {swampexpansion@NONE DONE}
forge-1.15.2-31.1.0-universal.jar Forge {[email protected] DONE}
Quark-r2.1-228.jar Quark {[email protected] DONE}
incubation-1.0.2-1.15.2.jar Incubation {[email protected] DONE}
FastLeafDecay-v20.jar FastLeafDecay {fastleafdecay@v20 DONE}
SoundFilters-0.13_for_1.15.2.jar Sound Filters {[email protected]_for_1.15.2 DONE}
Player Count: 1 / 8; [ServerPlayerEntity['KrolinTrevoler'/281, l='Prop', x=102.24, y=67.00, z=19.25]]
Data Packs: vanilla, mod:ambientsounds (incompatible), mod:appleskin (incompatible), mod:autoreglib (incompatible), mod:autumnity, mod:backpacked (incompatible), mod:betterbedrockgenerator, mod:blur (incompatible), mod:carpetstairsmod, mod:cookingforblockheads (incompatible), mod:fastleafdecay, mod:forge (incompatible), mod:incubation, mod:journeymap (incompatible), mod:jrftl (incompatible), mod:mcwbridges, mod:mcwroofs, mod:mcwwindows, mod:naturescompass (incompatible), mod:oreexcavation (incompatible), mod:quark, mod:quarkoddities, mod:simplefarming, mod:simplylight (incompatible), mod:soundfilters (incompatible), mod:swampexpansion (incompatible), mod:waystones (incompatible)
Type: Integrated Server (map_client.txt)
Is Modded: Definitely; Client brand changed to 'forge'

Just got this too, again in conjunction with Fast Leaf Decay.
Forge: 31.1.24
Simple Farming: 1.2.7

Newest version of Fast Leaf Decay fixes this
https://www.curseforge.com/minecraft/mc-mods/fast-leaf-decay/files