app: 🌸 add context messages to assorted errors

this adds additional context to errors, so that an invalid transaction
error includes more information about why it was invalid, and where that
error occured.

crates/core/app/src/app/mod.rs

@@ -294,8 +294,10 @@ impl App {
 
     /// Wrapper function for [`Self::deliver_tx`]  that decodes from bytes.
     pub async fn deliver_tx_bytes(&mut self, tx_bytes: &[u8]) -> Result<Vec<abci::Event>> {
-        let tx = Arc::new(Transaction::decode(tx_bytes)?);
-        self.deliver_tx(tx).await
+        let tx = Arc::new(Transaction::decode(tx_bytes).context("decoding transaction")?);
+        self.deliver_tx(tx)
+            .await
+            .context("failed to deliver transaction")
     }
 
     pub async fn deliver_tx(&mut self, tx: Arc<Transaction>) -> Result<Vec<abci::Event>> {
@@ -335,8 +337,14 @@ impl App {
             async move { tx2.check_stateful(state2).await }.instrument(tracing::Span::current()),
         );
 
-        stateless.await??;
-        stateful.await??;
+        stateless
+            .await
+            .context("waiting for check_stateless check tasks")?
+            .context("check_stateless failed")?;
+        stateful
+            .await
+            .context("waiting for check_stateful tasks")?
+            .context("check_stateful failed")?;
 
         // At this point, the stateful checks should have completed,
         // leaving us with exclusive access to the Arc<State>.
@@ -350,9 +358,12 @@ impl App {
         let transaction = Arc::as_ref(&tx).clone();
         state_tx
             .put_block_transaction(height, transaction.into())
-            .await?;
+            .await
+            .context("storing transactions")?;
 
-        tx.execute(&mut state_tx).await?;
+        tx.execute(&mut state_tx)
+            .await
+            .context("executing transaction")?;
 
         // At this point, we've completed execution successfully with no errors,
         // so we can apply the transaction to the State. Otherwise, we'd have