java.lang.NullPointerException at org.esa.snap.core.gpf.internal.OperatorContext.isComputingImageOf(OperatorContext.java:1271) at org.esa.snap.core.gpf.internal.OperatorImage.computeRect(OperatorImage.java:72) at javax.media.jai.SourcelessOpImage.computeTile(Unknown Source) at com.sun.media.jai.util.SunTileScheduler.scheduleTile(Unknown Source) at javax.media.jai.OpImage.getTile(Unknown Source) at javax.media.jai.PlanarImage.getData(Unknown Source) at com.bc.ceres.glevel.MultiLevelImage.getData(MultiLevelImage.java:64) at org.esa.snap.core.gpf.internal.OperatorContext.getSourceTile(OperatorContext.java:449) at org.esa.snap.core.gpf.internal.OperatorContext.getSourceTile(OperatorContext.java:435) at org.esa.snap.core.gpf.internal.OperatorImageTileStack.computeRect(OperatorImageTileStack.java:116) [catch] at org.esa.snap.core.gpf.internal.OperatorImageTileStack.computeTile(OperatorImageTileStack.java:86) at com.sun.media.jai.util.SunTileScheduler.scheduleTile(Unknown Source) at javax.media.jai.OpImage.getTile(Unknown Source) at com.sun.media.jai.util.RequestJob.compute(Unknown Source) at com.sun.media.jai.util.WorkerThread.run(Unknown Source)