---- Minecraft Crash Report ----
// Don't do that.

Time: 11.12.19 11:26
Description: Initializing game

java.lang.RuntimeException: Could not execute entrypoint stage 'client' due to errors!
at net.fabricmc.loader.entrypoint.minecraft.hooks.EntrypointUtils.invoke0(EntrypointUtils.java:55)
at net.fabricmc.loader.entrypoint.minecraft.hooks.EntrypointUtils.invoke(EntrypointUtils.java:34)
at net.fabricmc.loader.entrypoint.minecraft.hooks.EntrypointClient.start(EntrypointClient.java:33)
at net.minecraft.class_310.(class_310.java:391)
at net.minecraft.client.main.Main.main(Main.java:164)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:567)
at net.fabricmc.loader.game.MinecraftGameProvider.launch(MinecraftGameProvider.java:193)
at net.fabricmc.loader.launch.knot.Knot.init(Knot.java:138)
at net.fabricmc.loader.launch.knot.KnotClient.main(KnotClient.java:26)
Suppressed: java.lang.NoClassDefFoundError: me/sargunvohra/mcmods/autoconfig1u/ConfigData
at java.base/java.lang.ClassLoader.defineClass1(Native Method)
at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016)
at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:151)
at net.fabricmc.loader.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:156)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
at com.misterpemodder.shulkerboxtooltip.impl.ShulkerBoxTooltip.onInitializeClient(ShulkerBoxTooltip.java:50)
at net.fabricmc.loader.entrypoint.minecraft.hooks.EntrypointUtils.invoke0(EntrypointUtils.java:48)
... 11 more
Caused by: java.lang.ClassNotFoundException: me.sargunvohra.mcmods.autoconfig1u.ConfigData
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:602)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
at net.fabricmc.loader.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:161)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
... 18 more

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

-- Head --
Thread: Render thread
Stacktrace:
at net.fabricmc.loader.entrypoint.minecraft.hooks.EntrypointUtils.invoke0(EntrypointUtils.java:55)
at net.fabricmc.loader.entrypoint.minecraft.hooks.EntrypointUtils.invoke(EntrypointUtils.java:34)
at net.fabricmc.loader.entrypoint.minecraft.hooks.EntrypointClient.start(EntrypointClient.java:33)
at net.minecraft.class_310.(class_310.java:391)

-- Initialization --
Details:
Stacktrace:
at net.minecraft.client.main.Main.main(Main.java:164)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:567)
at net.fabricmc.loader.game.MinecraftGameProvider.launch(MinecraftGameProvider.java:193)
at net.fabricmc.loader.launch.knot.Knot.init(Knot.java:138)
at net.fabricmc.loader.launch.knot.KnotClient.main(KnotClient.java:26)

-- System Details --
Details:
Minecraft Version: 1.15
Minecraft Version ID: 1.15
Operating System: Windows 10 (amd64) version 10.0
Java Version: 13.0.1, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode, sharing), Oracle Corporation
Memory: 648285152 bytes (618 MB) / 838860800 bytes (800 MB) up to 3221225472 bytes (3072 MB)
CPUs: 12
JVM Flags: 10 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -Xmx3G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:ParallelGCThreads=6 -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=16M
Launched Version: fabric-loader-0.7.2+build.174-1.15
Backend library: LWJGL version 3.2.2 build 10
Backend API: NO CONTEXT
GL Caps:
Using VBOs: Yes
Is Modded: Definitely; Client brand changed to 'fabric'
Type: Client (map_client.txt)
CPU:

Can you share the whole log?

That was the whole crash report. The log file is:

[12:30:47] [main/INFO]: Loading for game Minecraft 1.15
[12:30:49] [main/INFO]: [FabricLoader] Loading 5 mods: [email protected], [email protected]+f3d8141be4, [email protected]+build.174, [email protected]+1.15.0, [email protected]
[12:30:49] [main/INFO]: SpongePowered MIXIN Subsystem Version=0.8 Source=file:/C:/Users/xxx/AppData/Roaming/.minecraft/libraries/net/fabricmc/sponge-mixin/0.8+build.16/sponge-mixin-0.8+build.16.jar Service=Knot/Fabric Env=CLIENT
[12:30:50] [main/INFO]: Setting user: Heitzenberg

I think I know what the issue is, for the time being download fabric-api and put it in the mods folders

Okay, thanks in advance for fixing it! :)

If I understand the changelog for 1.4.4 correctly, FabricAPI will now always be required, correct?

Yes, the bundled fabric API was causing incompatibility issues with other mods.

Can you update the description of the mod to say Fabric-API is a dependency? I got the same error in 1.15.2, and this issue solved it. I don't think most people will search in closed issues.