0.6 error handling is quite annoying and it doesnt return the actual error message, it was fixed in 0.7 https://github.com/bitcoindevkit/rust-esplora-client/pull/58 0.7 depends on rust-bitcoin 0.31 so this would be blocked until https://github.com/lightningdevkit/rust-lightning/pull/3063 is completed