Improve / fix machine and uplc error reporting.

crates/aiken/src/cmd/tx/simulate.rs

@@ -149,7 +149,14 @@ pub fn exec(
                 );
             }
             Err(err) => {
-                eprintln!("{}", display_tx_error(&err));
+                eprintln!(
+                    "{} {}",
+                    "        Error"
+                        .if_supports_color(Stderr, |s| s.red())
+                        .if_supports_color(Stderr, |s| s.bold()),
+                    err.red()
+                );
+
                 process::exit(1);
             }
         }
@@ -157,46 +164,3 @@ pub fn exec(
 
     Ok(())
 }
-
-fn display_tx_error(err: &tx::error::Error) -> String {
-    let mut msg = format!(
-        "{} {}",
-        "        Error"
-            .if_supports_color(Stderr, |s| s.red())
-            .if_supports_color(Stderr, |s| s.bold()),
-        err.red()
-    );
-    match err {
-        tx::error::Error::RedeemerError { err, .. } => {
-            msg.push_str(&format!(
-                "\n{}",
-                display_tx_error(err)
-                    .lines()
-                    .skip(1)
-                    .collect::<Vec<_>>()
-                    .join("\n"),
-            ));
-            msg
-        }
-        tx::error::Error::Machine(_, _, traces) => {
-            msg.push_str(
-                traces
-                    .iter()
-                    .map(|s| {
-                        format!(
-                            "\n{} {}",
-                            "        Trace"
-                                .if_supports_color(Stderr, |s| s.yellow())
-                                .if_supports_color(Stderr, |s| s.bold()),
-                            s.if_supports_color(Stderr, |s| s.yellow())
-                        )
-                    })
-                    .collect::<Vec<_>>()
-                    .join("")
-                    .as_str(),
-            );
-            msg
-        }
-        _ => msg,
-    }
-}

crates/uplc/src/machine/error.rs

@@ -11,7 +11,7 @@ pub enum Error {
     InvalidStepKind(u8),
     #[error("Cannot evaluate an open term:\\n\\n{}", .0.to_pretty())]
     OpenTermEvaluated(Term<NamedDeBruijn>),
-    #[error("The provided Plutus code called 'error'.")]
+    #[error("The validator crashed / exited prematurely")]
     EvaluationFailure,
     #[error("Attempted to instantiate a non-polymorphic term:\n\n{0:#?}")]
     NonPolymorphicInstantiation(Value),
@@ -29,9 +29,13 @@ pub enum Error {
     PairTypeMismatch(Type),
     #[error("Empty List:\n\n{0:#?}")]
     EmptyList(Value),
-    #[error("A builtin received a term argument when something else was expected:\n\n{0}\n\nYou probably forgot to wrap the builtin with a force.")]
+    #[error(
+        "A builtin received a term argument when something else was expected:\n\n{0}\n\nYou probably forgot to wrap the builtin with a force."
+    )]
     UnexpectedBuiltinTermArgument(Term<NamedDeBruijn>),
-    #[error("A builtin expected a term argument, but something else was received:\n\n{0}\n\nYou probably have an extra force wrapped around a builtin")]
+    #[error(
+        "A builtin expected a term argument, but something else was received:\n\n{0}\n\nYou probably have an extra force wrapped around a builtin"
+    )]
     BuiltinTermArgumentExpected(Term<NamedDeBruijn>),
     #[error("Unable to unlift value because it is not a constant:\n\n{0:#?}")]
     NotAConstant(Value),

crates/uplc/src/tx/error.rs

@@ -8,59 +8,93 @@ use pallas_primitives::conway::Language;
 pub enum Error {
     #[error("{0}")]
     Address(#[from] pallas_addresses::Error),
-    #[error("Only shelley reward addresses can be a part of withdrawals")]
+    #[error("only shelley reward addresses can be a part of withdrawals")]
     BadWithdrawalAddress,
     #[error("{0}")]
     FlatDecode(#[from] pallas_codec::flat::de::Error),
     #[error("{0}")]
     FragmentDecode(#[from] pallas_primitives::Error),
-    #[error("{}\n\n{:#?}\n\n{}", .0, .1, .2.join("\n"))]
+    #[error("{}{}", .0, .2.iter()
+        .map(|trace| {
+            format!(
+                "\n{:>13} {}",
+                "Trace",
+                if trace.contains("\n") {
+                    trace.lines()
+                        .enumerate()
+                        .map(|(ix, row)| {
+                            if ix == 0 {
+                                row.to_string()
+                            } else {
+                                format!("{:>13} {}", "",
+                                    row
+                                )
+                            }
+                        })
+                        .collect::<Vec<_>>()
+                        .join("\n")
+                } else {
+                    trace.to_string()
+                }
+            )
+        })
+        .collect::<Vec<_>>()
+        .join("")
+        .as_str()
+    )]
     Machine(machine::Error, ExBudget, Vec<String>),
-    #[error("Native script can't be executed in phase-two")]
+
+    #[error("native script can't be executed in phase-two")]
     NativeScriptPhaseTwo,
-    #[error("Can't eval without redeemers")]
+    #[error("can't eval without redeemers")]
     NoRedeemers,
-    #[error("Mismatch in required redeemers: {} {}", .missing.join(" "), .extra.join(" "))]
+    #[error(
+        "mismatch in expected redeemers\n{:>13} {}\n{:>13} {}",
+        "Missing",
+        if .missing.is_empty() { "ø".to_string() } else { .missing.join(&format!("\n{:>13}", "")) },
+        "Unexpected",
+        if .extra.is_empty() { "ø".to_string() } else { .extra.join(&format!("\n{:>13}", "")) },
+    )]
     RequiredRedeemersMismatch {
         missing: Vec<String>,
         extra: Vec<String>,
     },
-    #[error("Extraneous redeemer")]
+    #[error("extraneous redeemer")]
     ExtraneousRedeemer,
-    #[error("Resolved Input not found.")]
+    #[error("resolved Input not found")]
     ResolvedInputNotFound(TransactionInput),
-    #[error("Redeemer points to a non-script withdrawal.")]
+    #[error("redeemer points to a non-script withdrawal")]
     NonScriptWithdrawal,
-    #[error("Stake credential points to a non-script withdrawal.")]
+    #[error("stake credential points to a non-script withdrawal")]
     NonScriptStakeCredential,
-    #[error("Cost model not found for language: {:?}.", .0)]
+    #[error("cost model not found for language\n{:>13} {:?}", "Language", .0)]
     CostModelNotFound(Language),
-    #[error("Wrong era, Please use Babbage or Alonzo: {0}")]
+    #[error("unsupported era, please use Conway\n{:>13} {0}", "Decoder error")]
     WrongEra(#[from] pallas_codec::minicbor::decode::Error),
-    #[error("Byron address not allowed in Plutus.")]
+    #[error("byron address not allowed when PlutusV2 scripts are present")]
     ByronAddressNotAllowed,
-    #[error("Inline datum not allowed in PlutusV1.")]
+    #[error("inline datum not allowed when PlutusV1 scripts are present")]
     InlineDatumNotAllowed,
-    #[error("Script and input reference not allowed in PlutusV1.")]
+    #[error("script and input reference not allowed in PlutusV1")]
     ScriptAndInputRefNotAllowed,
-    #[error("Address doesn't contain a payment credential.")]
+    #[error("address doesn't contain a payment credential")]
     NoPaymentCredential,
-    #[error("Missing required datum: {}", hash)]
+    #[error("missing required datum\n{:>13} {}", "Datum", hash)]
     MissingRequiredDatum { hash: String },
-    #[error("Missing required script: {}", hash)]
+    #[error("missing required script\n{:>13} {}", "Script", hash)]
     MissingRequiredScript { hash: String },
-    #[error("Missing required inline datum or datum hash in script input.")]
+    #[error("missing required inline datum or datum hash in script input")]
     MissingRequiredInlineDatumOrHash,
-    #[error("Redeemer points to an unsupported certificate type.")]
+    #[error("redeemer points to an unsupported certificate type")]
     UnsupportedCertificateType,
-    #[error("Redeemer ({}, {}): {}", tag, index, err)]
+    #[error("failed script execution\n{:>13} {}", format!("{}({})", tag, index), err)]
     RedeemerError {
         tag: String,
         index: u32,
         err: Box<Error>,
     },
-    #[error("Missing script for redeemer")]
+    #[error("missing script for redeemer")]
     MissingScriptForRedeemer,
-    #[error("Failed to apply parameters to Plutus script.")]
+    #[error("failed to apply parameters to Plutus script")]
     ApplyParamsError,
 }

crates/uplc/src/tx/phase_one.rs

@@ -39,23 +39,17 @@ pub fn validate_missing_scripts(
         .clone()
         .into_iter()
         .filter(|x| !received_hashes.contains(x))
-        .map(|x| format!("[Missing (sh: {x})]"))
+        .map(|x| x.to_string())
         .collect();
 
     let extra: Vec<_> = received_hashes
         .into_iter()
         .filter(|x| !needed_hashes.contains(x))
-        .map(|x| format!("[Extraneous (sh: {x:?})]"))
+        .map(|x| x.to_string())
         .collect();
 
     if !missing.is_empty() || !extra.is_empty() {
-        let missing_errors = missing.join(" ");
+        return Err(Error::RequiredRedeemersMismatch { missing, extra });
-        let extra_errors = extra.join(" ");
-
-        unreachable!(
-            "Mismatch in required scripts: {} {}",
-            missing_errors, extra_errors
-        );
     }
 
     Ok(())
@@ -191,18 +185,13 @@ pub fn has_exact_set_of_redeemers(
     let missing: Vec<_> = redeemers_needed
         .into_iter()
         .filter(|x| !wits_redeemer_keys.contains(&&x.0))
-        .map(|x| {
+        .map(|x| format!("{} (key: {:?}, purpose: {:?})", x.2, x.0, x.1,))
-            format!(
-                "[Missing (redeemer_key: {:?}, script_purpose: {:?}, script_hash: {})]",
-                x.0, x.1, x.2,
-            )
-        })
         .collect();
 
     let extra: Vec<_> = wits_redeemer_keys
         .into_iter()
         .filter(|x| !needed_redeemer_keys.contains(x))
-        .map(|x| format!("[Extraneous (redeemer_key: {x:?})]"))
+        .map(|x| format!("{x:?}"))
         .collect();
 
     if !missing.is_empty() || !extra.is_empty() {