Indexing completely fails if firehose goes down

Do you want to request a feature or report a bug?

Bug

What is the current behavior?

I'm running graph-node version 0.27.

My graph node is configured with both an RPC provider and a firehose source like so:

[chains.mainnet]
shard = "primary"
provider = [
    { label = "mainnet-default", transport = "rpc", url = "<url to rpc provider>", features = [] },
    { label = "firehose", details = { type = "firehose", url = "<url to firehose>"  }},
]

If I start graph-node and then kill my firehose instance, all indexing seems to stop, even though the rpc provider is still available.

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem.

1. start a firehose grpc server
2. start a graph node with a rpc and firehose provier
3. deploy a subgraph and verify that graph node starts indexing
4. kill the firehose server
5. deploy a new subgraph
6. see the new subgraph never starts indexing

What is the expected behavior?

I expect graph-node to gracefully fall back to the rpc provider when the firehose server isn't available (whether that's due to network issues or internal errors in the firehose server or anything else).

Reproduce el problema con la configuración [chains.mainnet] que contiene proveedores RPC y firehose: inicia la indexación, detén el servidor de firehose y despliega un nuevo subgraph. Inspecciona la selección de proveedores y el comportamiento durante el inicio de la indexación; después, verifica que el nuevo subgraph comience a indexar mediante RPC cuando firehose no esté disponible.