Bug-fix: taproot debugging

doc/tapscript-example-with-tap.md

@@ -158,7 +158,7 @@ $ bcli getrawtransaction ec409014a3b1e7171cf498726bc7bc8bd249a04b65f30c7b8cb5c30
 
 This will be our input transaction. Make note of the index in the vout array of our output -- in this case it is index 0. We need to keep that index and that hex value around, so let's save those as environment variables:
 ```Bash
-$ vin=0 # CONFIRM THIS OR THINGS WILL FAIL
+$ vout=0 # CONFIRM THIS OR THINGS WILL FAIL
 $ txin=020000000001010aa633878f200c80fc8ec88f13f746e5870be7373ad5d78d22e14a402d6c6fc20000000000feffffff02a086010000000000225120a5ba0871796eb49fb4caa6bf78e675b9455e2d66e751676420f8381d5dda8951c759f405000000001600147bf84e78c81b9fed7a47b9251d95b13d6ebac14102473044022017de23798d7a01946744421fbb79a48556da809a9ffdb729f6e5983051480991022052460a5082749422804ad2a25e6f8335d5cf31f69799cece4a1ccc0256d5010701210257e0052b0ec6736ee13392940b7932571ce91659f71e899210b8daaf6f17027500000000
 ```
 
@@ -173,7 +173,7 @@ First, we need to create a transaction that spends from these inputs.
 ```Bash
 $ bcli getnewaddress
 bcrt1qe6ed9zhaetg6ur7ze7quhy5m520gx35znudxan
-$ tx=$(bcli createrawtransaction '[{"txid":"ec409014a3b1e7171cf498726bc7bc8bd249a04b65f30c7b8cb5c3079cf8f271", "vout":0}]' '[{"bcrt1qe6ed9zhaetg6ur7ze7quhy5m520gx35znudxan":0.0009}]')
+$ tx=$(bcli createrawtransaction '[{"txid":"ec409014a3b1e7171cf498726bc7bc8bd249a04b65f30c7b8cb5c3079cf8f271", "vout":$vout}]' '[{"bcrt1qe6ed9zhaetg6ur7ze7quhy5m520gx35znudxan":0.0009}]')
 $ echo $tx
 020000000171f2f89c07c3b58c7b0cf3654ba049d28bbcc76b7298f41c17e7b1a3149040ec0000000000ffffffff01905f010000000000160014ceb2d28afdcad1ae0fc2cf81cb929ba29e83468200000000
 ```

doc/txs/p2tr-in

@@ -0,0 +1 @@
+02000000000101e8f6e9842ef28c0cd13aeda574a1c81cd901685a7fa9088928cabde5ce1c3da90000000000feffffff02c759f40500000000160014a6e938b0815930ba6a7a79a1b3af38769adf405ea086010000000000225120a5ba0871796eb49fb4caa6bf78e675b9455e2d66e751676420f8381d5dda89510247304402202fc3f24bf7288031677ddfab0124e4a4f61b35429e48f0144a15e742e7c9b12a022063db1de6fde01117fe492824397305b6d3919edb29da6bbbd451fcc0fe0a1fab01210257e0052b0ec6736ee13392940b7932571ce91659f71e899210b8daaf6f17027500000000

doc/txs/p2tr-tx

@@ -0,0 +1 @@
+02000000000101b24f16ad8fcc61be2e329b405d578fb773cc3ee5fdbdba59be2e919f1a216a990100000000ffffffff01905f0100000000001600145f4c6989b4059186244d02e77551dddd96c96a7701400fcc6202036476acaf4d464fa21b586f9430634e995269ba1e844311a4d44db4b18ecdbf9934da968100df40c45c43b39f76e47d924bf132736a80cf50c5ec3200000000

instance.cpp

@@ -188,7 +188,7 @@ bool Instance::setup_environment(unsigned int flags) {
     if (tx) {
         if (txin && txin_index > -1) {
             std::vector<CTxOut> spent_outputs;
-            spent_outputs.emplace_back(txin->vout[txin_index]);
+            spent_outputs.emplace_back(txin->vout[txin_vout_index]);
             if (tx->vin.size() == 1) {
                 txdata.Init(*tx.get(), std::move(spent_outputs), has_preamble);
             }

instance.h

@@ -22,6 +22,12 @@ class Instance {
     ECCVerifyHandle evh;
     CTransactionRef tx;
     CTransactionRef txin;
+    /*
+     * INPUT TX VOUT            TX VIN
+     * [0]                      [0]*    <-- txin_index==0
+     * [1]*                     [1]
+     *    `-- txin_vout_index==1
+     */
     int64_t txin_index;             ///< index of the input txid in tx's inputs
     int64_t txin_vout_index;        ///< index inside txin of the output to tx
     std::vector<CAmount> amounts;