Bug: code with foreach loops doesn't compile

[novusnota]

For example, the following:

import "@stdlib/deploy"; // for Deployable trait

fun mapTest(): Int {
    let m: map<Int, Cell> = emptyMap();

    m.set(1, beginCell().storeUint(100, 16).endCell());
    m.set(2, beginCell().storeUint(200, 16).endCell());
    m.set(3, beginCell().storeUint(300, 16).endCell());
    m.set(4, beginCell().storeUint(400, 16).endCell());

    let sum: Int = 0;
    foreach (k, v in m) {
        let s: Slice = v.beginParse(); // convert Cell to Slice
        sum += s.loadUint(16);         // sum the Slice values
    }

    return sum; // 1000
}

contract ForeachExample with Deployable {
    // notice the lack of explicit empty init() -- a feature of Tact 1.3.0
    get fun mapTest(): Int {
        return mapTest();
    }
}

gives non-descriptive error message while building: Error while building. Removing the foreach loop runs the build. Additionally, local compilation of such code works too, with or without foreach.

[anton-trunov]

Not sure I understand the solution in 09aaa73