Error in stdlib_math: mzn_in_root_context used outside of predicate

[zsmooter]

Here's a fairly minimal example that triggers this error:

function list of var int: func(var int: x) = [x div x];
any: test_var = [func(1)];

This is the output when running:

Running error_test.mzn
error_test:2.1-13
  in variable declaration for 'test_var'
stdlib_math:192.6-26
  in call 'mzn_in_root_context'
MiniZinc: evaluation error: mzn_in_root_context used outside of predicate
Process finished with non-zero exit code 1.
Finished in 215msec.

Tested on 2.9.3 and 2.9.4 "edge" build in MiniZinc Playground