RCP: FCA, if editor area is splitted, when closing a sub-area, the square constraint of CA chart leads to a null exception

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at org.txm.tbx.chartsengine.jfreechart.JFCChartsEngine.squareOffGraph(JFCChartsEngine.java:2470)
    at org.txm.rcchartsengine.jfreechart.themes.base.swing.ItemSelectionChartPanel$1.componentResized(ItemSelectionChartPanel.java:164)
    at java.awt.Component.processComponentEvent(Component.java:6342)
    at java.awt.Component.processEvent(Component.java:6296)

Steps to reproduce

• create a CA chart editor
• create a concordance editor
• move the concordance editor below the CA chart so the area splits in two parts
• close the bottom concordance editor

(from redmine: issue id 1668, created on 2016/02/10 by Sebastien Jacquot)

added charts type::bug + 1 deleted label

changed milestone to %TXM 0.8.0

(Also refact squareOffGraph() to squareOffChart() or squareOff())

(from redmine: written on 2016/02/10 by Sebastien Jacquot)

closed

assigned to @sjacquot