fix: frontend code crashing when there is no canister ID

[vporton]

Fix a bug with nonexistent canister.

Description

When there is no canister ID (e.g. an actor class for creating multiple canisters), frontend code was crashing on input like

import { idlFactory as CanDBPartitionIDL } from "../../../declarations/CanDBPartition";

How Has This Been Tested?

I tested on a real still closed-source software.

It compiled and worked.

Checklist:

• The title of this PR complies with Conventional Commits.
• I have edited the CHANGELOG accordingly.
• I have made corresponding changes to the documentation.

[vporton]

@chenyan-dfinity I am asking you to speed up accepting this pull request, because without it I have a trouble with work on my dapp.