avoid creating a histogram without range (fixes #11217)

Author: jef-n

src/core/raster/qgsrasterinterface.cpp

@@ -517,17 +517,20 @@ void QgsRasterInterface::cumulativeCut( int theBandNo,
 
   int mySrcDataType = srcDataType( theBandNo );
 
+  // Init to NaN is better than histogram min/max to catch errors
+  theLowerValue = std::numeric_limits<double>::quiet_NaN();
+  theUpperValue = std::numeric_limits<double>::quiet_NaN();
+
   //get band stats to specify real histogram min/max (fix #9793 Byte bands)
   QgsRasterBandStats stats = bandStatistics( theBandNo, QgsRasterBandStats::Min, theExtent, theSampleSize );
+  if( stats.maximumValue < stats.minimumValue )
+    return;
+
   // for byte bands make sure bin count == actual range
   int myBinCount = ( mySrcDataType == QGis::Byte ) ? int( ceil( stats.maximumValue - stats.minimumValue + 1 ) ) : 0;
   QgsRasterHistogram myHistogram = histogram( theBandNo, myBinCount, stats.minimumValue, stats.maximumValue, theExtent, theSampleSize );
   //QgsRasterHistogram myHistogram = histogram( theBandNo, 0, std::numeric_limits<double>::quiet_NaN(), std::numeric_limits<double>::quiet_NaN(), theExtent, theSampleSize );
 
-  // Init to NaN is better than histogram min/max to catch errors
-  theLowerValue = std::numeric_limits<double>::quiet_NaN();
-  theUpperValue = std::numeric_limits<double>::quiet_NaN();
-
   double myBinXStep = ( myHistogram.maximum - myHistogram.minimum ) / myHistogram.binCount;
   int myCount = 0;
   int myMinCount = ( int ) qRound( theLowerCount * myHistogram.nonNullCount );