[Demonstration 1]

[Buggy Method]
public YuckInstance lookupThis() {
    if (currentInstance.isPresent()) {
        return currentInstance.get();
    }
    Preconditions.checkArgument(previous.isPresent());
    return previous.get().lookupThis();
}

[Buggy Hunk]
Preconditions.checkArgument(previous.isPresent());

[Patch]
Preconditions.checkArgument(previous.isPresent(), "Not inside an instance.");

[Demonstration 2]

[Buggy Method]
public int getNonSecretChannels() {
    int channels = 0;
    for (Channel channel : this.channels) if (!channel.getMode(ChannelMode.SECRET))
        channels++;
    return channels;
}

[Buggy Hunk]
for (Channel channel : this.channels)

[Patch]
for (Channel channel : this.getChannels())

[Demonstration 3]

[Buggy Method]
private NativeSymbol getSelf(Object thisObj) {
    try {
        return (NativeSymbol) thisObj;
    } catch (ClassCastException cce) {
        throw ScriptRuntime.typeError("Symbol expected");
    }
}

[Buggy Hunk]
throw ScriptRuntime.typeError("Symbol expected");

[Patch]
throw ScriptRuntime.typeError1("msg.invalid.type", thisObj.getClass().getName());