Fix baseline NaN for no heaps in gate

psrdada_cpp/effelsberg/edd/src/GatedSpectrometer.cu

@@ -116,8 +116,12 @@ __global__ void update_baselines(float*  __restrict__ baseLineG0,
        NG1 += stats_G1[i];
     }
 
+    if (NG0 > 0)
         baseLineG0[0] = baseLineNG0[0] / NG0;
+
+    if (NG1 > 0)
         baseLineG1[0] = baseLineNG1[0] / NG1;
+
     baseLineNG0[0] = 0;
     baseLineNG1[0] = 0;
 }