hiddenapi: Error message when superclass not found

Print an error message when building class hierarchy and unable to
find a superclass. This typically means that the provided classpath
is inconsistent (superclass missing), or the order of classes is
incorrect (superclass after child class).

Bug: 131289033
Test: compiles
Change-Id: Ia82755cc90008e974ce22dd2ccced81257ca90f9
diff --git a/tools/hiddenapi/hiddenapi.cc b/tools/hiddenapi/hiddenapi.cc
index 937abd1..646e483 100644
--- a/tools/hiddenapi/hiddenapi.cc
+++ b/tools/hiddenapi/hiddenapi.cc
@@ -526,7 +526,11 @@
       }
 
       HierarchyClass* superclass = FindClass(dex_klass.GetSuperclassDescriptor());
-      CHECK(superclass != nullptr);
+      CHECK(superclass != nullptr)
+          << "Superclass " << dex_klass.GetSuperclassDescriptor()
+          << " of class " << dex_klass.GetDescriptor() << " from dex file \""
+          << dex_klass.GetDexFile().GetLocation() << "\" was not found. "
+          << "Either the superclass is missing or it appears later in the classpath spec.";
       klass.AddExtends(*superclass);
 
       for (const std::string_view& iface_desc : dex_klass.GetInterfaceDescriptors()) {