Moved checks location in transfer

contracts/eosio.token/eosio.token.cpp

@@ -75,12 +75,12 @@ void token::transfer( account_name from,
     require_recipient( from );
     require_recipient( to );
 
-    if ( quantity.symbol.precision() != st.supply.symbol.precision() )
-       quantity.adjust_precision( st.supply.symbol );
-
     eosio_assert( quantity.is_valid(), "invalid quantity" );
     eosio_assert( quantity.amount > 0, "must transfer positive quantity" );
 
+    if ( quantity.symbol.precision() != st.supply.symbol.precision() )
+       quantity.adjust_precision( st.supply.symbol );
+
     sub_balance( from, quantity, st );
     add_balance( to, quantity, st, from );
 }