[MC-122388] Backspacing an open curly bracket under certain conditions crashes the game

The bug

In certain scenarios, like the one described below, backspacing an open curly bracket will cause the game to freeze and crash.

The command used was so:

/setblock 2 69 -31 minecraft:lever{face:ceiling} replace

Under normal circumstances, this command has the incorrect notation and would return failure. The correct notation uses square brackets and an equals sign. However, the issue still remains in that placing the cursor in front of the open curly bracket and pressing backspace will immediately crash the console.

Although it would be easier to simply type the command correctly, it would be best to tie up any loose ends.

Crash report

17w47b: crash-2017-11-23_23.36.52-client.txt

Description: keyPressed event handler

java.lang.IllegalArgumentException: Non [a-z0-9/._-] character in path of location: minecraft:leverface:ceiling
	at mp.<init>(SourceFile:31)
	at mp.<init>(SourceFile:36)
	at mp.a(SourceFile:121)
	at cg.d(SourceFile:156)
	at cg.a(SourceFile:69)
	at cf.a(SourceFile:21)
	at cf.parse(SourceFile:14)
	at com.mojang.brigadier.tree.ArgumentCommandNode.parse(ArgumentCommandNode.java:55)
	at com.mojang.brigadier.CommandDispatcher.parseNodes(CommandDispatcher.java:169)
	at com.mojang.brigadier.CommandDispatcher.parseNodes(CommandDispatcher.java:191)
	at com.mojang.brigadier.CommandDispatcher.parseNodes(CommandDispatcher.java:191)
	at com.mojang.brigadier.CommandDispatcher.parse(CommandDispatcher.java:143)
	at bpd.h(SourceFile:161)
	at bpd.a(SourceFile:97)
	at bpd$$Lambda$581/1727093989.accept(Unknown Source)
	at bnm.a(SourceFile:145)
	at bnm.b(SourceFile:194)
	at bnm.keyPressed(SourceFile:326)
	at bpd.keyPressed(SourceFile:134)
	at bme.a(SourceFile:269)
	at bme$$Lambda$578/1998450406.run(Unknown Source)
	at bqb.a(SourceFile:428)
	at bme.a(SourceFile:267)
	at bme$$Lambda$110/2066315072.invoke(Unknown Source)
	at org.lwjgl.glfw.GLFWKeyCallbackI.callback(GLFWKeyCallbackI.java:23)
	at org.lwjgl.system.JNI.invokeV(Native Method)
	at org.lwjgl.glfw.GLFW.glfwPollEvents(GLFW.java:2520)
	at bmr.a(SourceFile:282)
	at bmh.b(SourceFile:843)
	at bmh.a(SourceFile:376)
	at net.minecraft.client.main.Main.main(SourceFile:134)