rpc: Always throw in getblockstats if -txindex is required

Previously blocks with only the coinbase transaction didn't cause
the RPC error even if the requested stats required -txindex and
it wasn't enabled.

src/rpc/blockchain.cpp

@@ -1798,6 +1798,10 @@ static UniValue getblockstats(const JSONRPCRequest& request)
     const bool do_calculate_weight = do_all || SetHasKeys(stats, "total_weight", "avgfeerate", "swtotal_weight", "avgfeerate", "feerate_percentiles", "minfeerate", "maxfeerate");
     const bool do_calculate_sw = do_all || SetHasKeys(stats, "swtxs", "swtotal_size", "swtotal_weight");
 
+    if (loop_inputs && !g_txindex) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "One or more of the selected stats requires -txindex enabled");
+    }
+
     CAmount maxfee = 0;
     CAmount maxfeerate = 0;
     CAmount minfee = MAX_MONEY;
@@ -1861,10 +1865,6 @@ static UniValue getblockstats(const JSONRPCRequest& request)
         }
 
         if (loop_inputs) {
-
-            if (!g_txindex) {
-                throw JSONRPCError(RPC_INVALID_PARAMETER, "One or more of the selected stats requires -txindex enabled");
-            }
             CAmount tx_total_in = 0;
             for (const CTxIn& in : tx->vin) {
                 CTransactionRef tx_in;

test/functional/rpc_getblockstats.py

@@ -169,6 +169,8 @@ class GetblockstatsTest(BitcoinTestFramework):
         assert_raises_rpc_error(-8, 'Invalid selected statistic aaa%s' % inv_sel_stat,
                                 self.nodes[0].getblockstats, hash_or_height=1, stats=['minfee' , 'aaa%s' % inv_sel_stat])
 
+        assert_raises_rpc_error(-8, 'One or more of the selected stats requires -txindex enabled',
+                                self.nodes[1].getblockstats, hash_or_height=1)
         assert_raises_rpc_error(-8, 'One or more of the selected stats requires -txindex enabled',
                                 self.nodes[1].getblockstats, hash_or_height=self.start_height + self.max_stat_pos)