fix: scala 3 default value from fields (#626)

zio-schema-derivation/shared/src/main/scala-3/zio/schema/DeriveSchema.scala

@@ -278,7 +278,8 @@ private case class DeriveSchema()(using val ctx: Quotes) {
     }
 
   private def defaultValues(from: Symbol): Predef.Map[String, Expr[Any]] =
-    (1 to from.primaryConstructor.paramSymss.size).toList.map(
+    val params = from.primaryConstructor.paramSymss.flatten.filter(!_.isTypeParam)
+    val result = (1 to params.size).toList.map(
       i =>
           from
             .companionClass
@@ -295,7 +296,8 @@ private case class DeriveSchema()(using val ctx: Quotes) {
               if (select.isExpr) select.asExpr
               else select.appliedToType(TypeRepr.of[Any]).asExpr
             }
-      ).zip(from.primaryConstructor.paramSymss.flatten.filter(!_.isTypeParam).map(_.name)).collect{ case (Some(expr), name) => name -> expr }.toMap
+      ).zip(params.map(_.name))
+    result.collect{ case (Some(expr), name) => name -> expr }.toMap
 
   private def fromConstructor(from: Symbol): scala.collection.Map[String, List[Expr[Any]]] = {
       val defaults = defaultValues(from)

zio-schema-json/shared/src/test/scala-3/zio/schema/codec/DefaultValueSpec.scala

@@ -0,0 +1,33 @@
+package zio.schema.codec
+
+import zio.Console._
+import zio._
+import zio.json.{ DeriveJsonEncoder, JsonEncoder }
+import zio.schema._
+import zio.test.Assertion._
+import zio.test.TestAspect._
+import zio.test.*
+
+object DefaultValueSpec extends ZIOSpecDefault {
+
+  def spec: Spec[TestEnvironment, Any] =
+    suite("Custom Spec")(
+      customSuite,
+    ) @@ timeout(90.seconds)
+
+  private val customSuite = suite("custom")(
+    suite("default value schema")(
+      test("default value at last field") {
+        val result = JsonCodec.jsonDecoder(Schema[WithDefaultValue]).decodeJson("""{"orderId": 1}""")
+        assertTrue(result.isRight)
+      }
+    )
+  )
+
+  case class WithDefaultValue(orderId:Int, description: String = "desc")
+
+  object WithDefaultValue {
+    implicit lazy val schema: Schema[WithDefaultValue] = DeriveSchema.gen[WithDefaultValue]
+  }
+
+}