Hi all. I am using Julia through Juno on a Mac, and got the following error today when I was trying to call the `optimize!`

function from JuMP

```
using JuMP, Ipopt
m_test = Model(with_optimizer(Ipopt.Optimizer, linear_solver = "ma57"))
@variable(m_test, x[i in 1:10], lower_bound = 0.0, upper_bound = 1.0)
@constraint(m_test, sum(x) == 1.0)
@objective(m_test, Min, sum(i * x[i] for i in 1:10))
JuMP.optimize!(m_test)
```

I can run my code through the terminal though. I am not sure what’s going on here. Any suggestions? Thanks.