Revert "*add From<Result<String, ()>> for ClientError"

This reverts commit a103982ff0.

ethers-providers/src/transports/http.rs

@@ -75,23 +75,6 @@ impl From<wasm_bindgen::JsValue> for JsonRpcError {
     }
 }
 
-impl From<Result<String, ()>> for ClientError {
-    fn from(result: Result<String, ()>) -> Self {
-        match result {
-            Ok(msg) => ClientError::JsonRpcError(JsonRpcError {
-                code: 0,
-                message: msg,
-                data: None,
-            }),
-            Err(_) => ClientError::JsonRpcError(JsonRpcError {
-                code: 0,
-                message: "response is not a string".to_string(),
-                data: None,
-            }),
-        }
-    }
-}
-
 #[cfg_attr(target_arch = "wasm32", async_trait(?Send))]
 #[cfg_attr(not(target_arch = "wasm32"), async_trait)]
 impl JsonRpcClient for Provider {