Fix non-deterministic TileNodeLinker instabilityCheck crash with zero…

[topquarkred]

nextInt(int bound) throws an IllegalArgumentException if bound is <= 0. If instabilityCheck is called with self.instability == 0, and this.worldObj.rand.nextInt(50) rolls a 0, this.worldObj.rand.nextInt(this.instability) would throw an uncaught exception.

Example crash stack trace, right after linking two node linkers:

java.lang.IllegalArgumentException: bound must be positive
        at java.base/java.util.Random.nextInt(Random.java:322)
        at RFB-Launch//tb.common.tile.TileNodeLinker.instabilityCheck(TileNodeLinker.java:171)
        at RFB-Launch//tb.common.tile.TileNodeLinker.func_145845_h(TileNodeLinker.java:133)
        at RFB-Launch//net.minecraft.world.World.func_72939_s(World.java:1939)
        at RFB-Launch//net.minecraft.world.WorldServer.func_72939_s(WorldServer.java:489)
        at RFB-Launch//net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:636)
        at RFB-Launch//net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:334)
        at RFB-Launch//net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:547)
        at RFB-Launch//net.minecraft.server.MinecraftServer.run(MinecraftServer.java:427)
        at RFB-Launch//net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:685)


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

-- Head --
Stacktrace:
        at java.base/java.util.Random.nextInt(Random.java:322)
        at RFB-Launch//tb.common.tile.TileNodeLinker.instabilityCheck(TileNodeLinker.java:171)
        at RFB-Launch//tb.common.tile.TileNodeLinker.func_145845_h(TileNodeLinker.java:133)

-- Block entity being ticked --
Details:
        Name: tb.nodeLinker // tb.common.tile.TileNodeLinker
        Block type: ID #2231 (tile.nodeLinker // tb.common.block.BlockNodeLinker)
        Block data value: 0 / 0x0 / 0b0000
        Block location: World: (-493,68,-197), Chunk: (at 3,4,11 in -31,-13; contains blocks -496,0,-208 to -481,255,-193), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
        Actual block type: ID #2231 (tile.nodeLinker // tb.common.block.BlockNodeLinker)
        Actual block data value: 0 / 0x0 / 0b0000
Stacktrace:
        at RFB-Launch//net.minecraft.world.World.func_72939_s(World.java:1939)
        at RFB-Launch//net.minecraft.world.WorldServer.func_72939_s(WorldServer.java:489)

[Alastors]

It's not non-deterministic, the rng function of code is insanely deterministic, but sure, looks fine