Save Filechooser initial directory crashes the application

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Caused by: java.lang.NullPointerException: Cannot invoke "java.io.File.exists()" because "d" is null at org.amapvox.gui.MainFrameController.saveAsTask(MainFrameController.java:699) at org.amapvox.gui.MainFrameController.onActionMenuSaveAsTask(MainFrameController.java:685)