Use thiserror for error handling with less boilerplate

src/aztec/encoder/token.rs

@@ -34,7 +34,7 @@ impl TokenType {
         match self {
             TokenType::Simple(a) => a.appendTo(bit_array, text),
             TokenType::BinaryShift(a) => a.appendTo(bit_array, text),
-            TokenType::Empty => Err(Exceptions::illegalStateWith(
+            TokenType::Empty => Err(Exceptions::illegal_state_with(
                 "cannot appendTo on Empty final item",
             )),
         }