Error: Could not find or load main class 

[20:42:30 INFO]: Half command: /usr/lib/jvm/java-8-openjdk/jre/bin/java  -Djava.library.path=/home/mniip/.minecraft/versions/18w21b/18w21b-natives-194779323586589 -Dminecraft.launcher.brand=java-minecraft-launcher -Dminecraft.launcher.version=1.6.89-j -cp /home/mniip/.minecraft/libraries/com/mojang/patchy/1.1/patchy-1.1.jar:/home/mniip/.minecraft/libraries/oshi-project/oshi-core/1.1/oshi-core-1.1.jar:/home/mniip/.minecraft/libraries/net/java/dev/jna/jna/4.4.0/jna-4.4.0.jar:/home/mniip/.minecraft/libraries/net/java/dev/jna/platform/3.4.0/platform-3.4.0.jar:/home/mniip/.minecraft/libraries/com/ibm/icu/icu4j-core-mojang/51.2/icu4j-core-mojang-51.2.jar:/home/mniip/.minecraft/libraries/net/sf/jopt-simple/jopt-simple/5.0.3/jopt-simple-5.0.3.jar:/home/mniip/.minecraft/libraries/com/paulscode/codecjorbis/20101023/codecjorbis-20101023.jar:/home/mniip/.minecraft/libraries/com/paulscode/codecwav/20101023/codecwav-20101023.jar:/home/mniip/.minecraft/libraries/com/paulscode/libraryjavasound/20101123/libraryjavasound-20101123.jar:/home/mniip/.minecraft/libraries/com/paulscode/soundsystem/20120107/soundsystem-20120107.jar:/home/mniip/.minecraft/libraries/io/netty/netty-all/4.1.9.Final/netty-all-4.1.9.Final.jar:/home/mniip/.minecraft/libraries/com/google/guava/guava/21.0/guava-21.0.jar:/home/mniip/.minecraft/libraries/org/apache/commons/commons-lang3/3.5/commons-lang3-3.5.jar:/home/mniip/.minecraft/libraries/commons-io/commons-io/2.5/commons-io-2.5.jar:/home/mniip/.minecraft/libraries/commons-codec/commons-codec/1.10/commons-codec-1.10.jar:/home/mniip/.minecraft/libraries/net/java/jinput/jinput/2.0.5/jinput-2.0.5.jar:/home/mniip/.minecraft/libraries/net/java/jutils/jutils/1.0.0/jutils-1.0.0.jar:/home/mniip/.minecraft/libraries/com/mojang/brigadier/0.1.25/brigadier-0.1.25.jar:/home/mniip/.minecraft/libraries/com/google/code/gson/gson/2.8.0/gson-2.8.0.jar:/home/mniip/.minecraft/libraries/com/mojang/authlib/1.5.25/authlib-1.5.25.jar:/home/mniip/.minecraft/libraries/org/apache/commons/commons-compress/1.8.1/commons-compress-1.8.1.jar:/home/mniip/.minecraft/libraries/org/apache/httpcomponents/httpclient/4.3.3/httpclient-4.3.3.jar:/home/mniip/.minecraft/libraries/commons-logging/commons-logging/1.1.3/commons-logging-1.1.3.jar:/home/mniip/.minecraft/libraries/org/apache/httpcomponents/httpcore/4.3.2/httpcore-4.3.2.jar:/home/mniip/.minecraft/libraries/it/unimi/dsi/fastutil/7.1.0/fastutil-7.1.0.jar:/home/mniip/.minecraft/libraries/org/apache/logging/log4j/log4j-api/2.8.1/log4j-api-2.8.1.jar:/home/mniip/.minecraft/libraries/org/apache/logging/log4j/log4j-core/2.8.1/log4j-core-2.8.1.jar:/home/mniip/.minecraft/libraries/org/lwjgl/lwjgl/3.1.2/lwjgl-3.1.2.jar:/home/mniip/.minecraft/libraries/org/lwjgl/lwjgl-jemalloc/3.1.2/lwjgl-jemalloc-3.1.2.jar:/home/mniip/.minecraft/libraries/org/lwjgl/lwjgl-openal/3.1.2/lwjgl-openal-3.1.2.jar:/home/mniip/.minecraft/libraries/org/lwjgl/lwjgl-opengl/3.1.2/lwjgl-opengl-3.1.2.jar:/home/mniip/.minecraft/libraries/org/lwjgl/lwjgl-glfw/3.1.2/lwjgl-glfw-3.1.2.jar:/home/mniip/.minecraft/libraries/org/lwjgl/lwjgl-stb/3.1.2/lwjgl-stb-3.1.2.jar:/home/mniip/.minecraft/libraries/com/mojang/text2speech/1.10.3/text2speech-1.10.3.jar:/home/mniip/.minecraft/versions/18w21b/18w21b.jar net.minecraft.client.main.Main