game version：20w16a
Fabric loader 0.8.2 build 194

Command: "C:\Program Files\Java\jre1.8.0_45\bin\java.exe" -Dminecraft.client.jar=.minecraft\versions\20w16a\20w16a.jar -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=16M -XX:-UseAdaptiveSizePolicy -XX:-OmitStackTraceInFastThrow -Xmn128m -Xmx4096m -Dfml.ignoreInvalidMinecraftCertificates=true -Dfml.ignorePatchDiscrepancies=true -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump "-Djava.library.path=C:\Users\27303\Documents\Tencent Files\2291550517\FileRecv\test\XPLUS Snapshot\.minecraft\versions\20w16a\natives" -Dminecraft.launcher.brand=HMCL -Dminecraft.launcher.version=3.3.162 -cp "C:\Users\27303\Documents\Tencent Files\2291550517\FileRecv\test\XPLUS Snapshot\.minecraft\libraries\net\fabricmc\tiny-mappings-parser\0.2.2.14\tiny-mappings-parser-0.2.2.14.jar;C:\Users\27303\Documents\Tencent Files\2291550517\FileRecv\test\XPLUS Snapshot\.minecraft\libraries\net\fabricmc\sponge-mixin\0.8+build.18\sponge-mixin-0.8+build.18.jar;C:\Users\27303\Documents\Tencent Files\2291550517\FileRecv\test\XPLUS Snapshot\.minecraft\libraries\net\fabricmc\tiny-remapper\0.2.2.64\tiny-remapper-0.2.2.64.jar;C:\Users\27303\Documents\Tencent Files\2291550517\FileRecv\test\XPLUS Snapshot\.minecraft\libraries\net\fabricmc\fabric-loader-sat4j\2.3.5.4\fabric-loader-sat4j-2.3.5.4.jar;C:\Users\27303\Documents\Tencent Files\2291550517\FileRecv\test\XPLUS Snapshot\.minecraft\libraries\com\google\jimfs\jimfs\1.1\jimfs-1.1.jar;C:\Users\27303\Documents\Tencent Files\2291550517\FileRecv\test\XPLUS Snapshot\.minecraft\libraries\org\ow2\asm\asm\8.0\asm-8.0.jar;C:\Users\27303\Documents\Tencent Files\2291550517\FileRecv\test\XPLUS Snapshot\.minecraft\libraries\org\ow2\asm\asm-analysis\8.0\asm-analysis-8.0.jar;C:\Users\27303\Documents\Tencent Files\2291550517\FileRecv\test\XPLUS Snapshot\.minecraft\libraries\org\ow2\asm\asm-commons\8.0\asm-commons-8.0.jar;C:\Users\27303\Documents\Tencent Files\2291550517\FileRecv\test\XPLUS Snapshot\.minecraft\libraries\org\ow2\asm\asm-tree\8.0\asm-tree-8.0.jar;C:\Users\27303\Documents\Tencent Files\2291550517\FileRecv\test\XPLUS Snapshot\.minecraft\libraries\org\ow2\asm\asm-util\8.0\asm-util-8.0.jar;C:\Users\27303\Documents\Tencent Files\2291550517\FileRecv\test\XPLUS Snapshot\.minecraft\libraries\com\google\guava\guava\21.0\guava-21.0.jar;C:\Users\27303\Documents\Tencent Files\2291550517\FileRecv\test\XPLUS Snapshot\.minecraft\libraries\net\fabricmc\intermediary\20w16a\intermediary-20w16a.jar;C:\Users\27303\Documents\Tencent Files\2291550517\FileRecv\test\XPLUS Snapshot\.minecraft\libraries\net\fabricmc\fabric-loader\0.8.2+build.194\fabric-loader-0.8.2+build.194.jar;C:\Users\27303\Documents\Tencent Files\2291550517\FileRecv\test\XPLUS Snapshot\.minecraft\versions\20w16a\20w16a.jar" net.fabricmc.loader.launch.knot.KnotClient
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/logging/log4j/LogManager
at net.fabricmc.loader.launch.common.FabricLauncherBase.(FabricLauncherBase.java:44)
at net.fabricmc.loader.launch.knot.KnotClient.main(KnotClient.java:26)
Caused by: java.lang.ClassNotFoundException: org.apache.logging.log4j.LogManager
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 2 more

Is this a bug with HMCL that it does not include any Minecraft libraries in the classpath? I see no minecraft libraries on the classpath, such as gson, lwjgl, log4j (guava is there though)

Try with a different launcher or launch vanilla 20w16a before running the fabric game.

你这个启动命令行……怀疑是hmcl没设置好，启动的classpath里面没有minecraft本身的库，只有fabric的库。试试看启动原版后再启动带mod的，一般别的启动器都要获得原版的快照版本后才能加载fabric/forge的版本（依赖关系）

This appears to be a bug with HMCL, not with Fabric. Ensure that you have the latest version of HMCL, then try reporting the issue at https://github.com/huanghongxun/HMCL/issues.