fix(login): surface raw response body for non-JSON auth errors (fixes #305)

[c-reichert]

Fixes #305.

Problem

When the Bring backend rejects credentials with a text/plain body — most commonly Invalid Email. for a syntactically-bogus address — resp.json() throws SyntaxError and the existing catch surfaces:

• Node 20+/Bun: Cannot Login: Failed to parse JSON
• Node 18: Cannot Login: Unexpected token I in JSON at position 0

The actual server message is silently discarded, so callers cannot distinguish wrong-email from wrong-password from a rate-limit response.

Fix

Read the body as text first, then attempt JSON.parse. If parsing fails, surface the raw response (status + first 500 chars of body) verbatim in the thrown error message. Otherwise behavior is identical to before: a JSON body with an error field continues to flow through the existing 'error' in data branch, so the upstream email password combination not existing test path is preserved.

async login(): Promise<void> {
    let resp: Response;
    let bodyText: string;

    try {
        resp = await fetch(`${this.url}bringauth`, {
            method: 'POST',
            body: new URLSearchParams({ email: this.mail, password: this.password })
        });
        bodyText = await resp.text();
    } catch (e: any) {
        throw new Error(`Cannot Login: ${e.message}`);
    }

    let data: AuthResponse;
    try {
        data = JSON.parse(bodyText);
    } catch {
        const snippet = bodyText.trim().slice(0, 500) || '(empty body)';
        throw new Error(`Cannot Login: ${resp.status} ${snippet}`);
    }

    if ('error' in data) {
        throw new Error(`Cannot Login: ${data.message}`);
    }
    // …
}

Before / After

// Before, with a syntactically-bogus email:
Cannot Login: Failed to parse JSON

// After:
Cannot Login: 401 Invalid Email.

Tests

npm test (test/testMinimal.js, example@example.com / secret) still passes — that path returns JSON with email password combination not existing, and the 'error' in data branch handles it as before:

  Wrong login test
    ✔ init should take less than 2000ms (542ms)
    ✔ init should throw invalid JWT error (120ms)

  2 passing (666ms)

Scope

This PR only touches login(). The same resp.json() → 'error' in data pattern in loadLists, getItems, getItemsDetails, etc. has the same failure mode under e.g. rate-limit responses, but those are out of scope here — happy to follow up with a separate PR if you'd like.

Build

build/bring.js and build/bring.js.map regenerated via npm run build (TS 4.8 / committed tsconfig.build.json), matching how the existing build/ is committed in the repo.