feat: add utility for extracting error message

coder · code-asher · May 26, 2022 · May 26, 2022 · May 26, 2022 · May 27, 2022
commit c2a185150b2a02af07b89afef423f68d6c2718cb
@@ -0,0 +1,20 @@
+import { errorString, Language } from "./error"
+
+describe("error", () => {
+  describe("errorStr", () => {
+    it("returns message if error", () => {
+      expect(errorString(new Error("foobar"))).toBe("foobar")
+    })
+    it("returns message if string", () => {
+      expect(errorString("bazzle")).toBe("bazzle")
+    })
+    it("returns message if undefined or empty", () => {
+      expect(errorString(undefined)).toBe(Language.noError)
+      expect(errorString("")).toBe(Language.noError)
+    })
+    it("returns message if anything else", () => {
+      expect(errorString({ qux: "fred" })).toBe(Language.unexpectedError)
+      expect(errorString({ qux: 1 })).toBe(Language.unexpectedError)
+    })
+  })
+})
@@ -0,0 +1,20 @@
+export const Language = {
+  unexpectedError: "Unexpected error: see console for details",
+  noError: "No error provided",
+}
+
+/**
+ * Best effort to get a string from what could be an error or anything else.
+ */
+export const errorString = (error: Error | unknown): string | undefined => {
+  if (error instanceof Error) {
+    return error.message
+  } else if (typeof error === "string") {
+    return error || Language.noError
+  } else if (typeof error !== "undefined") {
+    console.warn(error)
+    return Language.unexpectedError
+  } else {
+    return Language.noError
+  }
+}