substreams init Polygon Amoy (testnet) unable to stream

[maoueh]

If you select Polygon Amoy in substreams init EVM Minimal example, you can compile with substreams build correctly but trying to run it with your StreamingFast API key configured leads to an error:

...
Error: rpc error: code = NotFound desc = unknown api key

This is because StreamingFast doesn't provide a Polygon Amoy testnet and the actual default endpoint used by substreams run when doing Substreams request to network: amoy is https://amoy.substreams.pinax.network:443 and of course, it doesn't accept StreamingFast API key.

We should think about emitting a small extra message in those cases that explain how to properly authenticate with Pinax.