fix(log): Fix confusing comments and error messages in zebra-checkpoints (#6579)

* Fix confusing comments and error messages in zebra-checkpoints

* Fix version in comment to verbosity

---------

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

zebra-consensus/src/checkpoint/list/tests.rs

@@ -280,8 +280,8 @@ fn checkpoint_list_hard_coded_max_gap_testnet() -> Result<(), BoxError> {
 /// Check that the hard-coded checkpoints are within [`MAX_CHECKPOINT_HEIGHT_GAP`],
 /// and a calculated minimum number of blocks. This also checks the heights are in order.
 ///
-/// We can't test [`MAX_CHECKPOINT_BYTE_COUNT`] directly, because we don't have access to the
+/// We can't test [`MAX_CHECKPOINT_BYTE_COUNT`] directly, because we don't have access to a large
-/// entire blockchain in the tests. Instead, we check the number of maximum-size blocks in a
+/// enough blockchain in the tests. Instead, we check the number of maximum-size blocks in a
 /// checkpoint. (This is ok, because the byte count only impacts performance.)
 fn checkpoint_list_hard_coded_max_gap(network: Network) -> Result<(), BoxError> {
     let _init_guard = zebra_test::init();

zebra-utils/src/bin/zebra-checkpoints/main.rs

@@ -14,7 +14,7 @@ use std::{ffi::OsString, process::Stdio};
 use std::os::unix::process::ExitStatusExt;
 
 use color_eyre::{
-    eyre::{ensure, Result},
+    eyre::{ensure, eyre, Result},
     Help,
 };
 use itertools::Itertools;
@@ -166,8 +166,14 @@ async fn main() -> Result<()> {
     // Zcash reorg limit.
     let height_limit = height_limit
         - HeightDiff::try_from(MIN_TRANSPARENT_COINBASE_MATURITY).expect("constant fits in i32");
-    let height_limit =
+    let height_limit = height_limit
-        height_limit.expect("node has some mature blocks: wait for it to sync more blocks");
+        .ok_or_else(|| {
+            eyre!(
+                "checkpoint generation needs at least {:?} blocks",
+                MIN_TRANSPARENT_COINBASE_MATURITY
+            )
+        })
+        .with_suggestion(|| "Hint: wait for the node to sync more blocks")?;
 
     // Start at the next block after the last checkpoint.
     // If there is no last checkpoint, start at genesis (height 0).
@@ -180,7 +186,8 @@ async fn main() -> Result<()> {
 
     assert!(
         starting_height < height_limit,
-        "No mature blocks after the last checkpoint: wait for node to sync more blocks"
+        "checkpoint generation needs more blocks than the starting height {starting_height:?}. \
+         Hint: wait for the node to sync more blocks"
     );
 
     // set up counters
@@ -232,15 +239,19 @@ async fn main() -> Result<()> {
 
                 let block_bytes: Vec<u8> = hex::decode(block_bytes)?;
 
-                // TODO: is it faster to call both `getblock height 0` and `getblock height 1`,
+                // TODO: is it faster to call both `getblock height verbosity=0`
-                //       rather than deserializing the block and calculating its hash?
+                //       and `getblock height verbosity=1`, rather than deserializing the block
+                //       and calculating its hash?
+                //
+                // It seems to be fast enough for checkpoint updates for now,
+                // but generating the full list takes more than an hour.
                 let block: Block = block_bytes.zcash_deserialize_into()?;
 
                 (
                     block.hash(),
                     block
                         .coinbase_height()
-                        .expect("block has always a coinbase height"),
+                        .expect("valid blocks always have a coinbase height"),
                     block_bytes.len().try_into()?,
                 )
             }