X_RPC_FAILED
Means
an RPC call failed without a problem+json body
Typical cause
registered, thrown by nothing since 21.0.0. Until then it was what a typed client answered for a gateway, a network fault, a non-JSON response, or a body whose code is not a framework code in X_ SCREAMING_SNAKE form. All of those are X_CLIENT_TRANSPORT_FAILED now, from actions and queries alike. RpcFailedError stays exported, because a shipped code never changes meaning
Fix
match X_CLIENT_TRANSPORT_FAILED instead: isUltimateError(e) && e.code === 'X_CLIENT_TRANSPORT_FAILED', with isUltimateError from @ultimat3/core