logging: fetch errors not handled when getting slot number from consensus client

[alexghr]

An error should be logged here:

aztec-packages/yarn-project/blob-sink/src/client/http.ts

Lines 341 to 346 in 4c3453b

	if (res.ok) {
	const body = await res.json();
	// Add one to get the slot number of the original block hash
	return Number(body.data.header.message.slot) + 1;
	}