Print the correct type in the top level chain as the message indicates (#21127)

src/compiler/checker.ts

@@ -23005,7 +23005,7 @@ namespace ts {
                             Diagnostics.Property_0_in_type_1_is_not_assignable_to_the_same_property_in_base_type_2,
                             unescapeLeadingUnderscores(declaredProp.escapedName),
                             typeToString(typeWithThis),
-                            typeToString(getTypeOfSymbol(baseProp))
+                            typeToString(baseWithThis)
                         );
                         if (!checkTypeAssignableTo(getTypeOfSymbol(prop), getTypeOfSymbol(baseProp), member.name || member, /*message*/ undefined, rootChain)) {
                             issuedMemberError = true;