Fixing compiler warning C4101

Github-Pull: #4856

src/rpcrawtransaction.cpp

@@ -543,7 +543,7 @@ Value signrawtransaction(const Array& params, bool fHelp)
             ssData >> tx;
             txVariants.push_back(tx);
         }
-        catch (std::exception &e) {
+        catch (const std::exception &) {
             throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "TX decode failed");
         }
     }