Fix broken StacktraceRecoveryTest

Author: sandwwraith

formats/json/jvmTest/src/kotlinx/serialization/StacktraceRecoveryTest.kt

@@ -9,13 +9,15 @@ import kotlinx.serialization.descriptors.*
 import kotlinx.serialization.encoding.*
 import kotlinx.serialization.json.*
 import kotlinx.serialization.json.internal.*
+import kotlinx.serialization.modules.*
 import kotlin.test.*
 
 class StacktraceRecoveryTest {
     @Serializable
     private class Data(val s: String)
 
     private class BadDecoder : AbstractDecoder() {
+        override val serializersModule: SerializersModule = EmptySerializersModule
         override fun decodeElementIndex(descriptor: SerialDescriptor): Int = 42
     }