Fix NPE caused by non-qualifier in superclasses (PY-31285)

python/psi-api/src/com/jetbrains/python/psi/stubs/PyClassStub.java

@@ -32,7 +32,8 @@ import java.util.Map;
 public interface PyClassStub extends NamedStub<PyClass> {
 
   /**
-  * @return a {@code Map} which contains imported class names as keys and their original names as values
+  * @return a {@code Map} which contains imported class names as keys and their original names as values.
+  * <i>Note: the returned {@code Map} could contain nulls as keys and as values.</i>
   */
   @NotNull
   Map<QualifiedName, QualifiedName> getSuperClasses();

python/src/com/jetbrains/python/codeInsight/typing/PyTypingTypeProvider.java

@@ -525,7 +525,7 @@ public class PyTypingTypeProvider extends PyTypeProviderBase {
         if (pyClass != null && scopeOwner instanceof PyFunction) {
           final PyResolveContext resolveContext = PyResolveContext.noImplicits().withTypeEvalContext(context);
 
-          boolean isInstanceAttribute = false;
+          boolean isInstanceAttribute;
           if (context.maySwitchToAST(target)) {
             isInstanceAttribute = StreamEx.of(PyUtil.multiResolveTopPriority(target.getQualifier(), resolveContext))
               .select(PyParameter.class)
@@ -709,6 +709,7 @@ public class PyTypingTypeProvider extends PyTypeProviderBase {
       }
     }
     for (QualifiedName qName : allBaseClassesQNames) {
+      if (qName == null) continue;
       final List<PsiElement> classes = PyResolveUtil.resolveQualifiedNameInScope(qName, (PyFile)pyClass.getContainingFile(), context);
       // Better way to handle results of the multiresove
       final PyClass firstFound = ContainerUtil.findInstance(classes, PyClass.class);