Make sure to check if requested image exists, otherwise return null. Also...

Make sure to check if requested image exists, otherwise return null. Also check for out of bound id values in the histogram and limit them

kstars/fitsviewer/fitshistogram.cpp

@@ -121,6 +121,8 @@ void FITSHistogram::constructHistogram(int hist_width, int hist_height)
 
         if (id >= hist_width)
             id = hist_width - 1;
+        else if (id < 0)
+            id=0;
 
         //histArray[id]++;
         histArray[id]++;

kstars/fitsviewer/fitsviewer.cpp

@@ -554,15 +554,12 @@ void FITSViewer::applyFilter(int ftype)
 
 FITSView * FITSViewer::getImage(int fitsUID)
 {
-    //if (fitsUID < 0 || fitsUID >= fitsImages.size())
-      //  return NULL;
-
     FITSTab *tab = fitsMap.value(fitsUID);
 
-    return tab->getImage();
-
-    //return fitsImages[fitsUID]->getImage();
-
+    if (tab)
+        return tab->getImage();
+    else
+        return NULL;
 }
 
 #include "fitsviewer.moc"