I tried to start minecraft with the RLCraft-Mod (RLCraft 1.12.2 - Release v2.9.1c) profile. Right after pressing play at the launcher it crashes with an error code 1.

forge 14.23.5.2860

Log:

[09:09:55] [main/DEBUG]: Running coremod plugin for FMLCorePlugin \{net.minecraftforge.fml.relauncher.FMLCorePlugin\}
[09:09:55] [main/DEBUG]: Running coremod plugin FMLCorePlugin
[09:09:56] [main/FATAL]: Patcher expecting non-empty class data file for net.minecraft.entity.passive.EntityOcelot, but received empty.
[09:09:56] [main/ERROR]: Unable to launch
java.lang.RuntimeException: java.lang.RuntimeException: Patcher expecting non-empty class data file for net.minecraft.entity.passive.EntityOcelot, but received empty, your vanilla jar may be corrupt.
    at net.minecraftforge.fml.relauncher.CoreModManager$FMLPluginWrapper.injectIntoClassLoader(CoreModManager.java:169) ~[forge-1.12.2-14.23.5.2860.jar:?]
    at net.minecraft.launchwrapper.Launch.launch(Launch.java:115) [launchwrapper-1.12.jar:?]
    at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.12.jar:?]
Caused by: java.lang.RuntimeException: Patcher expecting non-empty class data file for net.minecraft.entity.passive.EntityOcelot, but received empty, your vanilla jar may be corrupt.
    at net.minecraftforge.fml.common.patcher.ClassPatchManager.applyPatch(ClassPatchManager.java:114) ~[forge-1.12.2-14.23.5.2860.jar:?]
    at net.minecraftforge.fml.common.patcher.ClassPatchManager.getPatchedResource(ClassPatchManager.java:77) ~[forge-1.12.2-14.23.5.2860.jar:?]
    at net.minecraftforge.fml.common.asm.transformers.deobf.FMLDeobfuscatingRemapper.getFieldType(FMLDeobfuscatingRemapper.java:219) ~[forge-1.12.2-14.23.5.2860.jar:?]
    at net.minecraftforge.fml.common.asm.transformers.deobf.FMLDeobfuscatingRemapper.parseField(FMLDeobfuscatingRemapper.java:192) ~[forge-1.12.2-14.23.5.2860.jar:?]
    at net.minecraftforge.fml.common.asm.transformers.deobf.FMLDeobfuscatingRemapper.setup(FMLDeobfuscatingRemapper.java:161) ~[forge-1.12.2-14.23.5.2860.jar:?]
    at net.minecraftforge.fml.common.asm.FMLSanityChecker.injectData(FMLSanityChecker.java:187) ~[forge-1.12.2-14.23.5.2860.jar:?]
    at net.minecraftforge.fml.relauncher.CoreModManager$FMLPluginWrapper.injectIntoClassLoader(CoreModManager.java:164) ~[forge-1.12.2-14.23.5.2860.jar:?]
    ... 2 more
[09:09:56] [main/INFO]: [java.lang.ThreadGroup:uncaughtException:1052]: net.minecraftforge.fml.relauncher.FMLSecurityManager$ExitTrappedException
[09:09:56] [main/INFO]: [java.lang.ThreadGroup:uncaughtException:1052]:     at net.minecraftforge.fml.relauncher.FMLSecurityManager.checkPermission(FMLSecurityManager.java:49)
[09:09:56] [main/INFO]: [java.lang.ThreadGroup:uncaughtException:1052]:     at java.lang.SecurityManager.checkExit(SecurityManager.java:761)
[09:09:56] [main/INFO]: [java.lang.ThreadGroup:uncaughtException:1052]:     at java.lang.Runtime.exit(Runtime.java:107)
[09:09:56] [main/INFO]: [java.lang.ThreadGroup:uncaughtException:1052]:     at java.lang.System.exit(System.java:971)
[09:09:56] [main/INFO]: [java.lang.ThreadGroup:uncaughtException:1052]:     at net.minecraft.launchwrapper.Launch.launch(Launch.java:138)
[09:09:56] [main/INFO]: [java.lang.ThreadGroup:uncaughtException:1052]:     at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

The version you are using is no longer supported on this forum. Please update to a modern version of Minecraft to receive support. Currently supported versions are 1.19.2 (Latest) and 1.18.2 (LTS).

Understood, but the version of minecraft is set by the mod. 

Btw., I fixed the issue meanwhile by copiiing the install folder of a working instance into mine.