DiffractionExperiment: Remove potential bug with control reaching function without returning value

common/DiffractionExperiment.cpp

@@ -1412,7 +1412,7 @@ IndexingAlgorithmEnum DiffractionExperiment::GetIndexingAlgorithm() const {
             return IndexingAlgorithmEnum::FFBIDX;
         case IndexingAlgorithmEnum::FFT:
             return IndexingAlgorithmEnum::FFT;
-        case IndexingAlgorithmEnum::None:
+        default:
             return IndexingAlgorithmEnum::None;
     }
 }