Note also that rather than
on_boundary and near(x[0], 0)
you should use
on_boundary and near(x[0], 0.0, 1.0e-10)
the function near uses a very strict tolerance.
Note also that rather than
on_boundary and near(x[0], 0)
you should use
on_boundary and near(x[0], 0.0, 1.0e-10)
the function near uses a very strict tolerance.