[AI review feedback] Fix bugs

Author: nikhilsu

modules/openapi-generator/src/main/resources/scala-sttp/additionalTypeSerializers.mustache

@@ -48,7 +48,6 @@ trait AdditionalTypeSerializers {
   implicit final lazy val FileDecoder: Decoder[File] = Decoder[Array[Byte]].emap { bytes =>
     try {
       val tmpFile = File.createTempFile("download", ".tmp")
-      tmpFile.deleteOnExit()
       Files.write(tmpFile.toPath, bytes)
       Right(tmpFile)
     } catch {
@@ -64,6 +63,12 @@ trait AdditionalTypeSerializers {
 
   implicit final lazy val AnyEncoder: Encoder[Any] = Encoder.instance {
     case json: Json => json
+    case b: Boolean => Json.fromBoolean(b)
+    case n: Int => Json.fromInt(n)
+    case n: Long => Json.fromLong(n)
+    case n: Double => Json.fromDoubleOrNull(n)
+    case n: BigDecimal => Json.fromBigDecimal(n)
+    case s: String => Json.fromString(s)
     case other => Json.fromString(other.toString)
   }
 }

modules/openapi-generator/src/main/resources/scala-sttp/model.mustache

@@ -31,6 +31,7 @@ case class {{classname}}(
 )
 {{#circe}}
 object {{classname}} {
+{{#hasVars}}
   implicit val encoder{{classname}}: Encoder[{{classname}}] = Encoder.instance { t =>
     Json.fromFields{
       Seq(
@@ -51,6 +52,15 @@ object {{classname}} {
       {{/vars}}
     )
   }
+{{/hasVars}}
+{{^hasVars}}
+  implicit val encoder{{classname}}: Encoder[{{classname}}] = Encoder.instance { _ =>
+    Json.fromFields(Seq.empty)
+  }
+  implicit val decoder{{classname}}: Decoder[{{classname}}] = Decoder.instance { _ =>
+    Right({{classname}}())
+  }
+{{/hasVars}}
 }
 {{/circe}}
 {{/isEnum}}