feat: add error messages for CreateWithPersistError Display implementation

Author: luisschwab

wallet/src/wallet/persisted.rs

@@ -6,10 +6,16 @@ use core::{
     pin::Pin,
 };
 
-use alloc::boxed::Box;
+use alloc::{
+    boxed::Box,
+    string::{String, ToString},
+};
 use chain::Merge;
 
-use crate::{descriptor::DescriptorError, ChangeSet, CreateParams, LoadParams, Wallet};
+use crate::{
+    descriptor::{calc_checksum, DescriptorError},
+    ChangeSet, CreateParams, LoadParams, Wallet,
+};
 
 /// Trait that persists [`PersistedWallet`].
 ///
@@ -363,16 +369,38 @@ pub enum CreateWithPersistError<E> {
 impl<E: fmt::Display> fmt::Display for CreateWithPersistError<E> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            Self::Persist(err) => fmt::Display::fmt(err, f),
-            Self::DataAlreadyExists(changeset) => write!(
-                f,
-                "Cannot create wallet in persister which already contains wallet data: {:?}",
-                changeset
-            ),
-            Self::Descriptor(err) => fmt::Display::fmt(&err, f),
+            Self::Persist(err) => write!(f, "Persistence error: {}", err),
+            Self::DataAlreadyExists(changeset) => {
+                write!(f, "{}", changeset_info(changeset))
+            }
+            Self::Descriptor(err) => {
+                write!(f, "{err}")
+            }
         }
     }
 }
 
+/// Helper function to write basic fingerprinting information about a changeset
+fn changeset_info(changeset: &ChangeSet) -> String {
+    let network = match &changeset.network {
+        Some(network) => network.to_string(),
+        None => "None".to_string(),
+    };
+    let external_checksum = match &changeset.descriptor {
+        Some(descriptor) => calc_checksum(&descriptor.to_string()).unwrap(),
+        None => "[no external descriptor in the changeset]".to_string(),
+    };
+    let internal_checksum = match &changeset.change_descriptor {
+        Some(descriptor) => calc_checksum(&descriptor.to_string()).unwrap(),
+        None => "[no internal descriptor in the changeset]".to_string(),
+    };
+
+    format!(
+        "Cannot create wallet in a persister which already contains wallet data: \
+        Network: {}, External Descriptor Checksum: {}, Internal Descriptor Checksum: {}",
+        network, external_checksum, internal_checksum
+    )
+}
+
 #[cfg(feature = "std")]
 impl<E: fmt::Debug + fmt::Display> std::error::Error for CreateWithPersistError<E> {}