Refactor old code to properly raise Exceptions instead of returning error dictionaries

[fusion44]

See:

blitz_api/app/bitcoind/utils.py

Line 69 in 72862f8

async def bitcoin_rpc_async(method: str, params: list = []) -> coroutine:

Example:

    except aiohttp.client_exceptions.ClientConnectionError as e:
        return {
            "error": f"Aiohttp client connection error: {str(e)}",
            "status": status.HTTP_503_SERVICE_UNAVAILABLE,
        }

utils.py - redis_get():

blitz_api/app/api/utils.py

Line 57 in 72862f8

async def redis_get(key: str) -> str:

This function returns an empty string when a key is not found in Redis. This is not good. An empty string could be a valid value for a key. The caller can get confused whether the result is an error or just an empty string.