Display error codes better.

This is a *slight* hack / abuse of the code() method as we are now
  doing a bit of formatting within that function. Yet, we only do so at
  the very top-level (i.e. project's Error) because we can't actually
  fiddle with how miette presents errors.

crates/aiken-project/src/error.rs

@@ -262,31 +262,45 @@ impl Diagnostic for Error {
     }
 
     fn code<'a>(&'a self) -> Option<Box<dyn Display + 'a>> {
+        fn boxed<'a>(s: Box<dyn Display + 'a>) -> Box<dyn Display + 'a> {
+            Box::new(format!(
+                "        {} {}",
+                "Error"
+                    .if_supports_color(Stdout, |s| s.red())
+                    .if_supports_color(Stdout, |s| s.bold()),
+                format!("{s}").if_supports_color(Stdout, |s| s.red())
+            ))
+        }
+
         match self {
-            Error::DuplicateModule { .. } => Some(Box::new("aiken::module::duplicate")),
+            Error::DuplicateModule { .. } => Some(boxed(Box::new("aiken::module::duplicate"))),
             Error::FileIo { .. } => None,
-            Error::Blueprint(e) => e.code(),
-            Error::ImportCycle { .. } => Some(Box::new("aiken::module::cyclical")),
-            Error::Parse { .. } => Some(Box::new("aiken::parser")),
-            Error::Type { error, .. } => Some(Box::new(format!(
+            Error::Blueprint(e) => e.code().map(boxed),
+            Error::ImportCycle { .. } => Some(boxed(Box::new("aiken::module::cyclical"))),
+            Error::Parse { .. } => Some(boxed(Box::new("aiken::parser"))),
+            Error::Type { error, .. } => Some(boxed(Box::new(format!(
                 "aiken::check{}",
                 error.code().map(|s| format!("::{s}")).unwrap_or_default()
-            ))),
+            )))),
             Error::StandardIo(_) => None,
             Error::MissingManifest { .. } => None,
-            Error::TomlLoading { .. } => Some(Box::new("aiken::loading::toml")),
+            Error::TomlLoading { .. } => Some(boxed(Box::new("aiken::loading::toml"))),
             Error::Format { .. } => None,
-            Error::TestFailure { path, .. } => Some(Box::new(path.to_str().unwrap_or(""))),
+            Error::TestFailure { path, .. } => Some(boxed(Box::new(path.to_str().unwrap_or("")))),
             Error::Http(_) => Some(Box::new("aiken::packages::download")),
             Error::ZipExtract(_) => None,
             Error::JoinError(_) => None,
-            Error::UnknownPackageVersion { .. } => Some(Box::new("aiken::packages::resolve")),
-            Error::UnableToResolvePackage { .. } => Some(Box::new("aiken::package::download")),
+            Error::UnknownPackageVersion { .. } => {
+                Some(boxed(Box::new("aiken::packages::resolve")))
+            }
+            Error::UnableToResolvePackage { .. } => {
+                Some(boxed(Box::new("aiken::package::download")))
+            }
             Error::Json { .. } => None,
             Error::MalformedStakeAddress { .. } => None,
             Error::NoValidatorNotFound { .. } => None,
             Error::MoreThanOneValidatorFound { .. } => None,
-            Error::Module(e) => e.code(),
+            Error::Module(e) => e.code().map(boxed),
         }
     }
 
@@ -532,14 +546,24 @@ impl Diagnostic for Warning {
     }
 
     fn code<'a>(&'a self) -> Option<Box<dyn Display + 'a>> {
+        fn boxed<'a>(s: Box<dyn Display + 'a>) -> Box<dyn Display + 'a> {
+            Box::new(format!(
+                "      {} {}",
+                "Warning"
+                    .if_supports_color(Stdout, |s| s.yellow())
+                    .if_supports_color(Stdout, |s| s.bold()),
+                format!("{s}").if_supports_color(Stdout, |s| s.yellow())
+            ))
+        }
+
         match self {
-            Warning::Type { warning, .. } => Some(Box::new(format!(
+            Warning::Type { warning, .. } => Some(boxed(Box::new(format!(
                 "aiken::check{}",
                 warning.code().map(|s| format!("::{s}")).unwrap_or_default()
-            ))),
-            Warning::NoValidators => Some(Box::new("aiken::check")),
+            )))),
+            Warning::NoValidators => Some(boxed(Box::new("aiken::check"))),
             Warning::DependencyAlreadyExists { .. } => {
-                Some(Box::new("aiken::packages::already_exists"))
+                Some(boxed(Box::new("aiken::packages::already_exists")))
             }
         }
     }

crates/aiken-project/src/script.rs

@@ -81,7 +81,7 @@ impl Display for EvalHint {
             )),
             _ => None,
         }
-        .ok_or(fmt::Error::default())?;
+        .ok_or(fmt::Error)?;
 
         f.write_str(&msg)
     }

crates/aiken-project/src/watch.rs

@@ -31,7 +31,7 @@ struct Summary {
 impl Display for Summary {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.write_str(&format!(
-            "{}\n    {} {}, {} {}",
+            "      {} {} {}, {} {}",
             "Summary"
                 .if_supports_color(Stderr, |s| s.purple())
                 .if_supports_color(Stderr, |s| s.bold()),
@@ -41,14 +41,16 @@ impl Display for Summary {
             } else {
                 "errors"
             }
-            .if_supports_color(Stderr, |s| s.red()),
+            .if_supports_color(Stderr, |s| s.red())
+            .if_supports_color(Stderr, |s| s.bold()),
             self.warning_count,
             if self.warning_count == 1 {
                 "warning"
             } else {
                 "warnings"
             }
-            .if_supports_color(Stderr, |s| s.yellow()),
+            .if_supports_color(Stderr, |s| s.yellow())
+            .if_supports_color(Stderr, |s| s.bold()),
         ))
     }
 }
@@ -107,7 +109,7 @@ where
         }
 
         eprintln!(
-            "\n{}",
+            "{}",
             Summary {
                 warning_count,
                 error_count: errs.len(),
@@ -117,7 +119,7 @@ where
         return Err(ExitFailure::into_report());
     } else {
         eprintln!(
-            "\n{}",
+            "{}",
             Summary {
                 error_count: 0,
                 warning_count