klocwork: fix risk issues

tools/hsbench/data_corpus.cpp

@@ -58,7 +58,10 @@ void readRow(sqlite3_stmt *statement, vector<DataBlock> &blocks,
     }
     auto internal_stream_index = stream_indices[stream_id];
 
-    assert(blob || bytes > 0);
+    if (!(blob &&  bytes > 0)) {
+        assert(0);
+        throw std::domain_error("Invalid blob or bytes from sqlite3.");
+    }
     blocks.emplace_back(id, stream_id, internal_stream_index,
                         string(blob, blob + bytes));
 }

tools/hsbench/main.cpp

@@ -740,6 +740,11 @@ u64a byte_size(const vector<DataBlock> &corpus_blocks) {
         total += block.payload.size();
     }
 
+    if (total == 0) {
+        assert(0);
+        throw std::invalid_argument("Empty corpus.");
+    }
+
     return total;
 }