feat: fault tolerant body handling

[shevernitskiy]

The issue was originally described here: #613

Short Summary:
We assume that the body will be valid JSON. However, it can be empty or contain invalid JSON in some unusual cases. This can cause the server to crash due to an uncaught error triggered by JSON parsing in some of the adapters.

It was suggested to wrap it in a function, but I think that is unnecessary. We already have a promise and just need to safely resolve it to a value that we can then validate.

I suggest catching all promises where a crash can occur and returning an empty object. In webhookCallback, we can perform basic validation by checking the update_id field. In the case of an invalid body, we should return a 400 status to the client. Here, we need to add an extra callback to the adapter interface.

I added some e2e test cases to check for 400 and 401 errors, but it takes some time (~300-350ms on my machine).

As of TODO: investigate deno bug that happens when this console logging is removed - I didn't notice any issues. Maybe it's fixed now?

Closes: #697

[KnorpelSenf]

Closes: #697

This is not true, it's still a property on the adapters rather than a function

[KnorpelSenf]

Making it a function will btw fix this

[shevernitskiy]

i just commited, but again late for 2 secs before you merged:)

function safeJsonParse(value: string, fallback = {} as any): any {
    try {
        return JSON.parse(value);
    } catch (_err) {
        return fallback;
    }
}

[KnorpelSenf]

Ah

[shevernitskiy]

Closes: #697

This is not true, it's still a property on the adapters rather than a function

but function wrapper is not needed now