Improper SIgns Interaction

KitUI Issue

[x] This issue isn't duplicated - you can check if it is by using the search bar located at the top left hand corner and select "Issues" on the left.
[x] This issue includes appropriate markdown for sections - e.g. code blocks for crash dumps.
[x] This issue is understandable in English.

Issue description

KitUI shows up with right click on any sign that has a blank first line. ...

Reproducing the issue

Create a sign.
Leave the first line empty and put anything on lines 2,3, and 4.
Finish creating the sign.
Right click on the sign.

Client information

PocketMine-MP Version: 1.7dev-571 (50f273c0416b14eb08248a4f3bccb4ca8ab79b4d) MCPE Version: Windows 10 v1.2.8 Plugin Version: v1.1.8 (via Poggit) PHP version: 7.2

Optional information

Currently, there doesn't appear to be any documentation that shows how to properly use Signs with KitUI, however, expected behavior would be that the first or last line of a sign intended to be used with KitUI should have something unique and easily identifiable as a kit interface sign. For example, first line of a Kit sign could be [KIT].

Infernus101 / KitUI