Null check

Author: caetera

Writer/MzMlSpectrumWriter.cs

@@ -1683,16 +1683,19 @@ private PrecursorListType ConstructPrecursorList(IScanEventBase scanEvent, int?
             if (selectedIonMz > ZeroDelta)
             {
                 var selectedIonIntensity = CalculatePrecursorPeakIntensity(_rawFile, precursorScanNumber, selectedIonMz);
-                ionCvParams.Add(new CVParamType
+                if (selectedIonIntensity != null)
                 {
-                    name = "peak intensity",
-                    value = selectedIonIntensity.ToString(),
-                    accession = "MS:1000042",
-                    cvRef = "MS",
-                    unitAccession = "MS:1000131",
-                    unitCvRef = "MS",
-                    unitName = "number of detector counts"
-                });
+                    ionCvParams.Add(new CVParamType
+                    {
+                        name = "peak intensity",
+                        value = selectedIonIntensity.ToString(),
+                        accession = "MS:1000042",
+                        cvRef = "MS",
+                        unitAccession = "MS:1000131",
+                        unitCvRef = "MS",
+                        unitName = "number of detector counts"
+                    });
+                }
             }
 
             precursor.selectedIonList.selectedIon[0].cvParam = ionCvParams.ToArray();