Fix deserialization issue when 'parameters' is missing.

Deserialize to an empty vector.

crates/aiken-project/src/blueprint/mod.rs

@@ -10,7 +10,7 @@ use std::fmt::{self, Debug, Display};
 use validator::{Purpose, Validator};
 
 #[derive(Debug, PartialEq, Clone, serde::Serialize, serde::Deserialize)]
-pub struct Blueprint<T> {
+pub struct Blueprint<T: Default> {
     pub preamble: Preamble,
     pub validators: Vec<Validator<T>>,
 }
@@ -55,7 +55,7 @@ impl Blueprint<Schema> {
 
 impl<T> Blueprint<T>
 where
-    T: Clone,
+    T: Clone + Default,
 {
     pub fn lookup(
         &self,

crates/aiken-project/src/blueprint/schema.rs

@@ -302,6 +302,12 @@ impl Data {
     }
 }
 
+impl Default for Schema {
+    fn default() -> Self {
+        Schema::Unit
+    }
+}
+
 impl Display for Schema {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let s = serde_json::to_string_pretty(self).map_err(|_| fmt::Error)?;

crates/aiken-project/src/blueprint/validator.rs

@@ -22,6 +22,7 @@ pub struct Validator<T> {
     pub datum: Option<Annotated<T>>,
     pub redeemer: Annotated<T>,
     #[serde(skip_serializing_if = "Vec::is_empty")]
+    #[serde(default)]
     pub parameters: Vec<Annotated<T>>,
     #[serde(flatten)]
     pub program: Program<DeBruijn>,