Randomic System.ArgumentException: 'Parameter is not valid' when dropping a block on the NodeEditor

[FandangoOnCore]

After implementing a custom drag and drop of the nodes from a toolbox form, when dropping a node on the NodeEditor an unhandled ArgumentException terminates the program. This seemingly happens at random.
The source of the exception is the DrawPath function of System.Drawing returning status == 2, hence the following CheckErrorStatus function is throwing StatusException.

The immediate workaround was to wrap

g.DrawPath(m_p_line_hover, m_gp_hover);

in a try-catch block, but I'm still unsure what the problem is.