Add error handling to utxo_snapshot.sh

Resolves bitcoin#27841

contrib/devtools/utxo_snapshot.sh

@@ -29,6 +29,15 @@ BITCOIN_CLI_CALL="${*} -rpcclienttimeout=9999999"
 # Block we'll invalidate/reconsider to rewind/fast-forward the chain.
 PIVOT_BLOCKHASH=$($BITCOIN_CLI_CALL getblockhash $(( GENERATE_AT_HEIGHT + 1 )) )
 
+# Trap any errors that occur
+trap 'err_handler $?' ERR
+
+err_handler() {
+  (>&2 echo "Restoring chain to original height; this may take a while")
+  ${BITCOIN_CLI_CALL} reconsiderblock "${PIVOT_BLOCKHASH}"
+  exit $1
+}
+
 (>&2 echo "Rewinding chain back to height ${GENERATE_AT_HEIGHT} (by invalidating ${PIVOT_BLOCKHASH}); this may take a while")
 ${BITCOIN_CLI_CALL} invalidateblock "${PIVOT_BLOCKHASH}"
 
@@ -40,5 +49,8 @@ else
   ${BITCOIN_CLI_CALL} dumptxoutset "${OUTPUT_PATH}"
 fi
 
+# Remove error trap
+trap - ERR
+
 (>&2 echo "Restoring chain to original height; this may take a while")
 ${BITCOIN_CLI_CALL} reconsiderblock "${PIVOT_BLOCKHASH}"