Canister has no query method '__motoko_async_helper'

[vporton]

Please use this repository to reprise the bug.

The following command produces a non-understandable error:

$ dfx deploy main && dfx canister call main main '()'
...
Error: Failed query call.
Caused by: The replica returned a rejection error: reject code CanisterReject, reject message Error from Canister fokw4-aeaaa-aaaaa-qaa3a-cai: Canister has no query method '__motoko_async_helper'..
Check that the method being called is exported by the target canister. See documentation: http://internetcomputer.org/docs/current/references/execution-errors#method-not-found, error code Some("IC0406")

Code extract:

import frontend "canister:frontend";

actor class Main() = this {
  public composite query func main() : async () {
    let b = this.f();
    let c = frontend.get({key = "/index.html"; accept_encodings = ["identity"]});
    ignore {{b0 = await b; c0 = await c}};
  };

  public query func f(): async () {};
};

My guess is that frontend may be written in Rust and not contain __motoko_async_helper.

[vporton]

$ moc --version
Motoko compiler 0.13.5+ (source v1dvjb2h-nhmkbsj8-k5v6kp5x-1gxvi6dg)

[vporton]

Oh, sorry, the example wasn't minimal. Corrected.