Can not catch a JuliaError caused by function blowing up to infinity

[unary-code]

JuliaError: Exception 'UndefVarError: integral not defined' occurred while calling julia code:

When I ran this code:
"
using QuadGK

try
integral, err = quadgk(x -> exp(1/(x-0.5)), 0, 1, rtol=1e-8)
catch
print("Error")
end
print(integral)
print(err)
"

I am generating a bunch of expression trees somewhat randomly, where each expression tree represents a particular function of x.
For example, one expression tree could be:
*
/
cos 5
|
x0
which represents the function "cos(x0)*5". I can call this function tree_as_func(x).

I need to run "quadgk(x -> tree_as_func(x), 0, 1, rtol=1e-8)" where "tree_as_func" is the function of x that the current expression tree represents.
I do not know if "tree_as_func(x)" blows up to infinity on the domain x=[0, 1) or if its integral over x=[0, 1) is infinity.

As a result, I need to be able to catch errors. But this try-catch block fails to catch the error.
How can I do this?

[stevengj]

That's not how Julia exceptions work. If quadgk throws an exception, e.g. due to your integrand blowing up, then it does not have a return value.

You could do

integral, err = try
    quadgk(....)
catch
    Inf, Inf
end

if you want to use Inf as the value when it throws an error, for example.

[stevengj]

If you have further questions about exceptions and try/catch syntax, I would suggest https://discourse.julialang.org/