refactor: move HttpFailure.toError to api module

Also expose EitherNet as an api dependency since it's part of the
public API.

api/src/main/kotlin/dev/msfjarvis/claw/api/util.kt

@@ -0,0 +1,21 @@
+/*
+ * Copyright © Harsh Shandilya.
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
+ */
+package dev.msfjarvis.claw.api
+
+import com.slack.eithernet.ApiResult.Failure
+import java.io.IOException
+import java.net.HttpURLConnection
+
+@Suppress("NOTHING_TO_INLINE") // We inline this to eliminate the stacktrace frame.
+inline fun <T : Any> Failure.HttpFailure<T>.toError(): Throwable =
+  when (code) {
+    HttpURLConnection.HTTP_NOT_FOUND -> IOException("Story was removed by moderator")
+    HttpURLConnection.HTTP_INTERNAL_ERROR,
+    HttpURLConnection.HTTP_BAD_GATEWAY,
+    HttpURLConnection.HTTP_UNAVAILABLE -> IOException("It appears lobste.rs is currently down")
+    else -> IOException("API returned an invalid response")
+  }