Support 1.15.x

[magneticflux-]

When starting on 1.15.x, I get this error:

java.lang.IllegalAccessError: tried to access field net.minecraft.class_310.field_1704 from class net.minecraft.class_757
	at net.minecraft.class_757.handler$zfe000$onUpdateTargetedEntityComplete(class_757.java:1584) ~[intermediary-minecraft-1.15.2-client.jar:?]
	at net.minecraft.class_757.method_3190(class_757.java:400) ~[intermediary-minecraft-1.15.2-client.jar:?]
	at net.minecraft.class_757.method_3188(class_757.java:915) ~[intermediary-minecraft-1.15.2-client.jar:?]
	at net.minecraft.class_757.method_3192(class_757.java:684) ~[intermediary-minecraft-1.15.2-client.jar:?]
	at net.minecraft.class_310.method_1523(class_310.java:989) ~[intermediary-minecraft-1.15.2-client.jar:?]
	at net.minecraft.class_310.method_1514(class_310.java:619) [intermediary-minecraft-1.15.2-client.jar:?]
	at net.minecraft.client.main.Main.main(Main.java:204) [intermediary-minecraft-1.15.2-client.jar:?]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_232]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_232]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_232]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_232]
	at net.fabricmc.loader.game.MinecraftGameProvider.launch(MinecraftGameProvider.java:193) [fabric-loader-0.7.8+build.184.jar:?]
	at net.fabricmc.loader.launch.knot.Knot.init(Knot.java:138) [fabric-loader-0.7.8+build.184.jar:?]
	at net.fabricmc.loader.launch.knot.KnotClient.main(KnotClient.java:26) [fabric-loader-0.7.8+build.184.jar:?]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_232]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_232]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_232]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_232]
	at org.multimc.onesix.OneSixLauncher.launchWithMainClass(OneSixLauncher.java:196) [NewLaunch.jar:?]
	at org.multimc.onesix.OneSixLauncher.launch(OneSixLauncher.java:231) [NewLaunch.jar:?]
	at org.multimc.EntryPoint.listen(EntryPoint.java:143) [NewLaunch.jar:?]
	at org.multimc.EntryPoint.main(EntryPoint.java:34) [NewLaunch.jar:?]

Here's a deobfuscated stack trace courtesy of NotEnoughCrashes:

java.lang.IllegalAccessError: tried to access field net.minecraft.class_310.field_1704 from class net.minecraft.class_757
    at Not Enough Crashes deobfuscated stack trace.(1.15.2+build.7)
    at net.minecraft.client.render.GameRenderer.handler$zfm000$onUpdateTargetedEntityComplete(GameRenderer:1584)
    at net.minecraft.client.render.GameRenderer.updateTargetedEntity(GameRenderer:400)
    at net.minecraft.client.render.GameRenderer.renderWorld(GameRenderer:915)
    at net.minecraft.client.render.GameRenderer.render(GameRenderer:684)
    at net.minecraft.client.MinecraftClient.render(MinecraftClient:989)
    at net.minecraft.client.MinecraftClient.run(MinecraftClient:619)
    at net.minecraft.client.main.Main.main(Main:204)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    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)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.multimc.onesix.OneSixLauncher.launchWithMainClass(OneSixLauncher.java:196)
    at org.multimc.onesix.OneSixLauncher.launch(OneSixLauncher.java:231)
    at org.multimc.EntryPoint.listen(EntryPoint.java:143)
    at org.multimc.EntryPoint.main(EntryPoint.java:34)

I'll try to update it myself and make a PR soon.