opa: 'opa build -t wasm' with functions defined on entrypoint fails with "undefined ref"

Short description

Everything builds and tests pass. When attempting to build for WASM:

opa build -e "reproduction" -t wasm reproduction.rego
error: 1 error occurred: reproduction.rego:1: rego_type_error: undefined ref: data.reproduction.func_decide
        data.reproduction.func_decide
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        have: (any) => object<bool: boolean>

Problem observed on 0.38.0, 0.37.2

Steps To Reproduce

reproduction.rego

package reproduction

func_not(y) = {"bool":false} {
    y.bool
} else = {"bool":true}

func_decide(something) = func_not(something)

reproduction_test.rego

package reproduction

test_repro {
    func_decide({"bool":false}).bool
}

Expected behavior

Successful WASM build or test build failing or tests not passing.

Additional context