evaluate: error out when existing set has incompatible key

evaluate: error out when existing set has incompatible key

Before:
BUG: invalid range expression type symbol
nft: expression.c:1494: range_expr_value_high: Assertion `0' failed.

After:
range_expr_value_high_assert:5:20-27: Error: Could not resolve protocol name
                elements = { 100-11.0.0.0, }
                                 ^^^^^^^^
range_expr_value_high_assert:7:6-7: Error: set definition has conflicting key (ipv4_addr vs inet_proto)

Signed-off-by: Florian Westphal <fw@strlen.de>