fix: biome CI check fails — formatting error in client.ts and non-null assertion warnings

[mehmetkr-31]

Description

Running bun run check:ci currently fails due to a formatting error and produces lint warnings:

1. Formatting error in src/core/client.ts (blocks CI)

The multi-line import of BridgeUnsupportedRouteError and BridgeValidationError does not match biome's expected single-line format:

- import {
-   BridgeUnsupportedRouteError,
-   BridgeValidationError,
- } from "./errors";
+ import { BridgeUnsupportedRouteError, BridgeValidationError } from "./errors";

2. Non-null assertion in src/core/protocol/engines/base-engine.ts:354

const event = msgInitEvents[0]!; // Forbidden non-null assertion

The array length is already checked above, so the ! is unnecessary and can be replaced with a proper guard.

3. Non-null assertion in src/core/protocol/routes/svm-to-base.ts:616

evmCall!, // Forbidden non-null assertion

evmCall is validated before this point, but the non-null assertion should be replaced with a proper narrowing check.

Reproduction

bun run check:ci
# Result: 1 error, 2 warnings

Expected behavior

bun run check:ci should pass with 0 errors and 0 warnings.