Improve exception message when failing to serialize anonymous object metadata

(See KT-20996)

Old message:

    Cannot get FQ name of local class: class <no name provided>

New message:

    Cannot get FQ name of local class: class <no name provided> defined in private fun x(): <no name provided> defined in root package in file 1.kt

compiler/serialization/src/org/jetbrains/kotlin/serialization/DescriptorAwareStringTable.kt

@@ -8,21 +8,26 @@ package org.jetbrains.kotlin.serialization
 import org.jetbrains.kotlin.descriptors.ClassifierDescriptorWithTypeParameters
 import org.jetbrains.kotlin.metadata.serialization.StringTable
 import org.jetbrains.kotlin.name.ClassId
+import org.jetbrains.kotlin.renderer.DescriptorRenderer
 import org.jetbrains.kotlin.resolve.descriptorUtil.classId
 import org.jetbrains.kotlin.types.ErrorUtils
 
 interface DescriptorAwareStringTable : StringTable {
     fun getFqNameIndex(descriptor: ClassifierDescriptorWithTypeParameters): Int {
         if (ErrorUtils.isError(descriptor)) {
-            throw IllegalStateException("Cannot get FQ name of error class: $descriptor")
+            throw IllegalStateException("Cannot get FQ name of error class: ${renderDescriptor(descriptor)}")
         }
 
         val classId = descriptor.classId
                 ?: getLocalClassIdReplacement(descriptor)
-                ?: throw IllegalStateException("Cannot get FQ name of local class: $descriptor")
+                ?: throw IllegalStateException("Cannot get FQ name of local class: ${renderDescriptor(descriptor)}")
 
         return getQualifiedClassNameIndex(classId.asString(), classId.isLocal)
     }
 
     fun getLocalClassIdReplacement(descriptor: ClassifierDescriptorWithTypeParameters): ClassId? = null
+
+    private fun renderDescriptor(descriptor: ClassifierDescriptorWithTypeParameters): String =
+        DescriptorRenderer.COMPACT.render(descriptor) + " defined in " +
+                DescriptorRenderer.FQ_NAMES_IN_TYPES.render(descriptor.containingDeclaration)
 }