Avoid test error.

johnmay · johnmay · commit 11a5d260635a · 2018-12-03T14:16:51.000Z
diff --git a/display/renderbasic/src/main/java/org/openscience/cdk/renderer/generators/standard/StandardAtomGenerator.java b/display/renderbasic/src/main/java/org/openscience/cdk/renderer/generators/standard/StandardAtomGenerator.java
@@ -139,7 +139,8 @@ AtomSymbol generateSymbol(IAtomContainer container, IAtom atom, HydrogenPosition
 
             // unset the mass if it's the major isotope (could be an option)
             Integer mass = atom.getMassNumber();
-            if (mass != null &&
+            if (number != 0 &&
+                mass != null &&
                 model != null &&
                 model.get(StandardGenerator.OmitMajorIsotopes.class) &&
                 isMajorIsotope(number, mass)) {
