deserialization error: result and error are mutually exclusive at line 1 column 245

[dreaded369]

I've just attempted to dockerize this app and get server mode functioning for a custom network - PulseChain.

It's up and running and sees the RPC etc... and I can see requests and responses get logged, but I'm getting this error:

token-bss-server-1  | 2025-06-24T04:27:24.918002Z  INFO token_bss_server: Added provider for chain: Pulsechain
token-bss-server-1  | 2025-06-24T04:27:24.964769Z  INFO token_bss_server::server: Server running on: 0.0.0.0:8080
token-bss-server-1  | 2025-06-24T04:27:48.621051Z  INFO token_bss_server::handlers: {"msg":"new_request","handler":"search_handler","id":"118486003142648920368154547958431666723","args":{"chain":"pulse","token":"0x0dEEd1486bc52aA0d3E6f8849cEC5adD6598A162"}}
token-bss-server-1  | 2025-06-24T04:27:48.622880Z  INFO token_bss_server::handlers: {"msg":"new_response","handler":"search_handler","id":"118486003142648920368154547958431666723","response":"{\"success\":false,\"error\":\"deserialization error: result and error are mutually exclusive at line 1 column 245: result and error are mutually exclusive at line 1 column 245\"}","duration":1,"source":"null"}
token-bss-server-1  | 2025-06-24T04:27:48.622907Z ERROR token_bss_server::handlers: deserialization error: result and error are mutually exclusive at line 1 column 245: result and error are mutually exclusive at line 1 column 245

Any ideas what this could point to?

[dreaded369]

I get the same error if I just pretend to be Ethereum but with the PulseChain RPC address (PulseChain is a fork of Ethereum so should work with this simple substitution).

[dreaded369]

If i remove the _RPC value, and so only have the ETHEREUM_FORK_RPC enabled, then I get a response but it's always:{"success":false,"error":"SlotNotFound"}
From the logs:
{"msg":"new_response","handler":"search_handler","id":"164021763073250906865689709072727771895","response":"{\"success\":false,\"error\":\"SlotNotFound\"}","duration":19,"source":"null"}