The KleeSlabs 1.14.4 release contains an old compat json for Botania (https://github.com/blay09/KleeSlabs/blob/1.14.x/src/main/resources/data/kleeslabs/kleeslabs_compat/botania.json) that does not work in 1.14.4.

Loading Botania alongside KleeSlabs at the moment causes an exception that breaks any further data packs from loading. In 1.14.4, resource locations can't have upper case characters (causing the below error), and Botania has renamed their slabs to suit. I don't currently have the time to update the json, but I think these exceptions should also be caught inside JsonCompatLoader, as having them thrown breaks other mods (in this case, the most obvious was Silent Gear).

[28Dec2019 01:04:02.570] [Server thread/ERROR] [net.minecraft.server.MinecraftServer/]: Failed to reload data packs java.util.concurrent.ExecutionException: net.minecraft.util.ResourceLocationException: Non [a-z0-9/._-] character in path of location: botania:quartzSlabDarkHalf at java.util.concurrent.CompletableFuture.reportGet(Unknown Source) ~[?:1.8.0_221] at java.util.concurrent.CompletableFuture.get(Unknown Source) ~[?:1.8.0_221] at net.minecraft.server.MinecraftServer.func_195568_a(MinecraftServer.java:1435) [?:?] at net.minecraft.server.MinecraftServer.func_195560_a(MinecraftServer.java:436) [?:?] at net.minecraft.server.MinecraftServer.func_71247_a(MinecraftServer.java:351) [?:?] at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:210) [?:?] at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:598) [?:?] at java.lang.Thread.run(Unknown Source) [?:1.8.0_221] Caused by: net.minecraft.util.ResourceLocationException: Non [a-z0-9/._-] character in path of location: botania:quartzSlabDarkHalf at net.minecraft.util.ResourceLocation.<init>(SourceFile:38) ~[?:?] at net.minecraft.util.ResourceLocation.<init>(SourceFile:47) ~[?:?] at net.blay09.mods.kleeslabs.registry.json.JsonCompatLoader.parseBlock(JsonCompatLoader.java:145) ~[?:7.4.7] at net.blay09.mods.kleeslabs.registry.json.JsonCompatLoader.load(JsonCompatLoader.java:95) ~[?:7.4.7] at net.blay09.mods.kleeslabs.registry.json.JsonCompatLoader.func_195410_a(JsonCompatLoader.java:37) ~[?:7.4.7] at net.minecraft.resources.IResourceManagerReloadListener.lambda$reload$0(IResourceManagerReloadListener.java:16) ~[?:?] at java.util.concurrent.CompletableFuture.uniRun(Unknown Source) ~[?:1.8.0_221] at java.util.concurrent.CompletableFuture$UniRun.tryFire(Unknown Source) ~[?:1.8.0_221] at java.util.concurrent.CompletableFuture$Completion.run(Unknown Source) ~[?:1.8.0_221] at net.minecraft.resources.AsyncReloader.func_219557_a(SourceFile:71) ~[?:?] at net.minecraft.util.concurrent.TickDelayedTask.run(SourceFile:18) ~[?:?] at net.minecraft.util.concurrent.ThreadTaskExecutor.func_213166_h(SourceFile:144) ~[?:?] at net.minecraft.util.concurrent.RecursiveEventLoop.func_213166_h(SourceFile:23) ~[?:?] at net.minecraft.util.concurrent.ThreadTaskExecutor.func_213168_p(SourceFile:118) ~[?:?] at net.minecraft.server.MinecraftServer.func_213205_aW(MinecraftServer.java:699) ~[?:?] at net.minecraft.server.MinecraftServer.func_213168_p(MinecraftServer.java:693) ~[?:?] at net.minecraft.util.concurrent.ThreadTaskExecutor.func_213161_c(SourceFile:127) ~[?:?] at net.minecraft.server.MinecraftServer.func_195568_a(MinecraftServer.java:1432) ~[?:?] ... 5 more