Can't add custom block with custom form with JS in it.

Hello all,

I made a module for OpenLayers this afternoon and I would like to use it when editing a node.
The module provides a simple block with a custom form inside, you can browse the code here.

I have enabled the "Node edit/add" panel, created a variant for a particular node type, and when I want to add the block, I get this error.

I have checked around the line 4462 of includes/common.inc and if I remove the property '#attached' of my form, I can add the block to the panel.

I'm still debugging ans trying to understand where it comes from, any help is greatly appreciated, thanks.