Add an error utility for messages and status codes

languageserver/src/utils/error.ts

@@ -0,0 +1,27 @@
+import {RequestError} from "@octokit/types";
+
+export function errorMessage(error: unknown): string {
+  if (error instanceof Error) {
+    return error.message;
+  }
+  if (typeof error === "string") {
+    return error;
+  }
+
+  if ("name" in (error as RequestError)) {
+    return (error as RequestError).name;
+  }
+
+  const status = errorStatus(error);
+  if (status) {
+    return `HTTP ${status}`;
+  }
+
+  return "Unknown error";
+}
+
+export function errorStatus(error: unknown): number | undefined {
+  if ("status" in (error as RequestError)) {
+    return (error as RequestError).status;
+  }
+}