WIP: remove catch by value

src/liblelantus/range_verifier.cpp

@@ -160,7 +160,7 @@ bool RangeVerifier::verify(const std::vector<std::vector<GroupElement> >& V, con
         // In the event of an attempt to invert a zero scalar, the batch is bad
         try {
             x_j_inv = LelantusPrimitives::invert(x_j); // NOTE: these could be batched across proofs as well for improved efficiency
-        } catch (std::runtime_error) {
+        } catch (const std::runtime_error&) {
             return false;
         }