Polynomial is not Divisible

[MarkCampbell90]

Hello,
I compiled following circom program using circom v2.1.9 and the flags --O0, --r1cs, --sym, --wasm, --c, --json

pragma circom 2.1.9;

template main_template() {

    signal input a;
    signal input b;
    signal input c;
    signal input d;

    signal output out;

    // var e = 1;   // <------ OK
    var e = 0;      // <------- ERROR
    var f = 1;

    signal tmp0;
    tmp0 <-- (a / b);

    signal tmp1;
    tmp1 <-- (c / d);

    // out <== (tmp0 * tmp1 * e + tmp0 * f);    // <----- OK
    out <== tmp0 * ( tmp1 * e + f);      // <----- ERROR
}

component main = main_template();

But when I try to generate and verify a proof using the generate witness generation and snarkjs with PLONK or FFLONK as proof system I get following error:

[ERROR] snarkJS: Error: Polynomial is not divisible
    at Polynomial.divZh (/usr/local/lib/node_modules/snarkjs/build/cli.cjs:7694:27)
    at computeT (/usr/local/lib/node_modules/snarkjs/build/cli.cjs:8734:23)
    at async round3 (/usr/local/lib/node_modules/snarkjs/build/cli.cjs:8568:9)
    at async plonk16Prove (/usr/local/lib/node_modules/snarkjs/build/cli.cjs:8243:5)
    at async Object.plonkProve [as action] (/usr/local/lib/node_modules/snarkjs/build/cli.cjs:13586:36)
    at async clProcessor (/usr/local/lib/node_modules/snarkjs/build/cli.cjs:481:27)

While playing around with it, I found out that the error disappears when:

• using the --O1 or --O2 flag,
• changing the RHS to (tmp0 * tmp1 * e + tmp0 * f),
• changing the value of e to a non zero value.

The inputs seem not to affect the behavior as I can change them freely without affecting the error.
The inputs I used are:

{
    "a" : 4,
    "b" : 6,
    "c" : 8,
    "d" : 9
}

I found this behavior very strange, especially how the error is not triggered by applying any of the listed changes.
Is this something on the circom or the snarkjs side ?