Merge pull request #11791 from Microsoft/genericTypeParameterConstraint

Check type parameters of the type alias declaration

src/compiler/checker.ts

@@ -17434,6 +17434,7 @@ namespace ts {
             checkGrammarDecorators(node) || checkGrammarModifiers(node);
 
             checkTypeNameIsReserved(node.name, Diagnostics.Type_alias_name_cannot_be_0);
+            checkTypeParameters(node.typeParameters);
             checkSourceElement(node.type);
         }