I have a large code that solves an optimization model. To keep the code clean I am trying to move the part that calls the optimizer and retrieve solution to a separate function. Even though I am able to solve the model this way, but retrieving the solution throws an error (`ERROR: LoadError: NoOptimizer()`

). An MWE is provided below:

```
function defineAndSolveModel()
model = Model()
@variables(model, begin
y1<=0
y2<=0
y3
end)
@constraint(model, con1, y1 + 2*y3 <= 3)
@constraint(model, con2, -2*y1 + y2- 3*y3 == 2)
@constraint(model, con3, 3*y1 + 3*y2- 7*y3 == -3)
@constraint(model, con4, 4*y1 - 4*y3 >= 4)
@objective(model, Max, 3*y1 - 5*y2 - 2*y3)
solution = solveModel(model)
return solution
end
function solveModel(model)
println(all_variables(model)) # prints VariableRef[y1, y2, y3]
set_optimizer(model, CPLEX.Optimizer)
optimize!(model) #The model solves successfully
#The two lines below throw error
sol = (value.(y1), value.(y2), value.(y3))
dualVars = (dual.(con1), dual.(con2), dual.(con3), dual.(con4))
return objective_value(model), sol, dualVars
end
defineAndSolveModel()
```

Can someone point out the issue here? Thank you.