Revert fix for #10831

[chrchr-github]

No description provided.

[chrchr-github]

This will reintroduce internalAstErrors for

struct A { std::string s; };
void f(A& a) {
   const auto b = [](const decltype(a.s)::value_type& v) {
      return 0;
   };
}

and

struct A { std::string s; };
void f(A& a) {
   const auto b { [](const decltype(a.s)::value_type& v) {
      return 0;
   } };
}

However the AST is incorrect as it is now. Maybe we should skip over lambdas in validateAST()?