Compatibility with custom recipe plugins

[bsergent]

Found by IrusVirus on GitHub and Foxzes on DevBukkit.

Desc

• Ugly NullPointerException with RecipeManager 2 but still works. (IrusVirus)
• Custom Crafting Recipes completely disables RealMail's recipes. (Foxzes)

Expected Cause
Null Pointer exception is self-explanatory, but I'm not sure why the other plugins disables my recipes.

Error Logs

RecipeManager 2

[11:48:27 ERROR]: Could not pass event CraftItemEvent to RealMail v0.3.2.16
org.bukkit.event.EventException
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:305) ~[spigot18-ADRUNDAAL.jar:git-Spigot-c3c767f-33d5de3]
at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigot18-ADRUNDAAL.jar:git-Spigot-c3c767f-33d5de3]
at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:502) [spigot18-ADRUNDAAL.jar:git-Spigot-c3c767f-33d5de3]
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:487) [spigot18-ADRUNDAAL.jar:git-Spigot-c3c767f-33d5de3]
at net.minecraft.server.v1_8_R1.PlayerConnection.a(PlayerConnection.java:1588) [spigot18-ADRUNDAAL.jar:git-Spigot-c3c767f-33d5de3]
at net.minecraft.server.v1_8_R1.PacketPlayInWindowClick.a(SourceFile:31) [spigot18-ADRUNDAAL.jar:git-Spigot-c3c767f-33d5de3]
at net.minecraft.server.v1_8_R1.PacketPlayInWindowClick.a(SourceFile:9) [spigot18-ADRUNDAAL.jar:git-Spigot-c3c767f-33d5de3]
at net.minecraft.server.v1_8_R1.PacketHandleTask.run(SourceFile:13) [spigot18-ADRUNDAAL.jar:git-Spigot-c3c767f-33d5de3]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_45-internal]
at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_45-internal]
at net.minecraft.server.v1_8_R1.MinecraftServer.z(MinecraftServer.java:696) [spigot18-ADRUNDAAL.jar:git-Spigot-c3c767f-33d5de3]
at net.minecraft.server.v1_8_R1.DedicatedServer.z(DedicatedServer.java:316) [spigot18-ADRUNDAAL.jar:git-Spigot-c3c767f-33d5de3]
at net.minecraft.server.v1_8_R1.MinecraftServer.y(MinecraftServer.java:634) [spigot18-ADRUNDAAL.jar:git-Spigot-c3c767f-33d5de3]
at net.minecraft.server.v1_8_R1.MinecraftServer.run(MinecraftServer.java:537) [spigot18-ADRUNDAAL.jar:git-Spigot-c3c767f-33d5de3]
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_45-internal]
Caused by: java.lang.NullPointerException
at com.challengercity.plugins.realmail.RealMail$MailListener.onCraft(RealMail.java:987) ~[?:?]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_45-internal]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_45-internal]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_45-internal]
at java.lang.reflect.Method.invoke(Method.java:497) ~[?:1.8.0_45-internal]
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:301) ~[spigot18-ADRUNDAAL.jar:git-Spigot-c3c767f-33d5de3]
... 14 more