Fix switch fallthrough warnings. (#387)

Author: g-easy

opencensus/exporters/stats/stackdriver/internal/stackdriver_utils.cc

@@ -77,6 +77,9 @@ google::api::MetricDescriptor::ValueType GetValueType(
           return google::api::MetricDescriptor::DOUBLE;
         case opencensus::stats::MeasureDescriptor::Type::kInt64:
           return google::api::MetricDescriptor::INT64;
+        default:
+          ABSL_ASSERT(false && "Unknown measure_descriptor type.");
+          return google::api::MetricDescriptor::DOUBLE;
       }
     case opencensus::stats::Aggregation::Type::kDistribution:
       return google::api::MetricDescriptor::DISTRIBUTION;

opencensus/stats/internal/view_data_impl.cc

@@ -41,16 +41,16 @@ ViewDataImpl::Type ViewDataImpl::TypeForDescriptor(
             case MeasureDescriptor::Type::kInt64:
               return ViewDataImpl::Type::kInt64;
             default:
-              ABSL_ASSERT(false && "Bad ViewDataImpl type.");
-              break;
+              ABSL_ASSERT(false && "Unknown measure_descriptor type.");
+              return ViewDataImpl::Type::kDouble;
           }
         case Aggregation::Type::kCount:
           return ViewDataImpl::Type::kInt64;
         case Aggregation::Type::kDistribution:
           return ViewDataImpl::Type::kDistribution;
         default:
-          ABSL_ASSERT(false && "Bad ViewDataImpl type.");
-          break;
+          ABSL_ASSERT(false && "Unknown aggregation type.");
+          return ViewDataImpl::Type::kDouble;
       }
     case AggregationWindow::Type::kInterval:
       return ViewDataImpl::Type::kStatsObject;