Allow logging functions to accept string[] directly

src/logging.test.ts

@@ -0,0 +1,17 @@
+import test from "ava";
+
+import { joinMessageStrings } from "./logging";
+import { setupTests } from "./testing-utils";
+
+setupTests(test);
+
+test("joinMessageStrings", async (t) => {
+  // For strings and errors, it is the identity function.
+  t.deepEqual(joinMessageStrings("Hello"), "Hello");
+
+  const error = new Error("Some error");
+  t.deepEqual(joinMessageStrings(error), error);
+
+  // For arrays of strings, we get a join-ed string.
+  t.deepEqual(joinMessageStrings(["foo", "bar"]), "foo bar");
+});