feat(server): add error handling middleware

Add global error handling middleware for Hono with:
- AppError class for application-specific errors with status codes
- Errors factory for common HTTP errors (badRequest, unauthorized, etc.)
- Consistent JSON error response format
- Tests covering all error types

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

1 files changed, 173 insertions, 0 deletions

diff --git a/pkgs/server/src/middleware/error-handler.test.ts b/pkgs/server/src/middleware/error-handler.test.ts
new file mode 100644
index 0000000..21d6fc1
--- /dev/null
+++ b/pkgs/server/src/middleware/error-handler.test.ts
@@ -0,0 +1,173 @@
+import { Hono } from "hono";
+import { describe, expect, it } from "vitest";
+import { AppError, Errors, errorHandler } from "./error-handler";
+
+function createTestApp() {
+	const app = new Hono();
+	app.onError(errorHandler);
+	return app;
+}
+
+describe("errorHandler", () => {
+	describe("AppError handling", () => {
+		it("returns correct status and message for AppError", async () => {
+			const app = createTestApp();
+			app.get("/test", () => {
+				throw new AppError("Custom error", 400, "CUSTOM_ERROR");
+			});
+
+			const res = await app.request("/test");
+			expect(res.status).toBe(400);
+			expect(await res.json()).toEqual({
+				error: {
+					message: "Custom error",
+					code: "CUSTOM_ERROR",
+				},
+			});
+		});
+
+		it("uses default values for AppError", async () => {
+			const app = createTestApp();
+			app.get("/test", () => {
+				throw new AppError("Something went wrong");
+			});
+
+			const res = await app.request("/test");
+			expect(res.status).toBe(500);
+			expect(await res.json()).toEqual({
+				error: {
+					message: "Something went wrong",
+					code: "INTERNAL_ERROR",
+				},
+			});
+		});
+	});
+
+	describe("Errors factory functions", () => {
+		it("handles badRequest error", async () => {
+			const app = createTestApp();
+			app.get("/test", () => {
+				throw Errors.badRequest("Invalid input");
+			});
+
+			const res = await app.request("/test");
+			expect(res.status).toBe(400);
+			expect(await res.json()).toEqual({
+				error: {
+					message: "Invalid input",
+					code: "BAD_REQUEST",
+				},
+			});
+		});
+
+		it("handles unauthorized error", async () => {
+			const app = createTestApp();
+			app.get("/test", () => {
+				throw Errors.unauthorized();
+			});
+
+			const res = await app.request("/test");
+			expect(res.status).toBe(401);
+			expect(await res.json()).toEqual({
+				error: {
+					message: "Unauthorized",
+					code: "UNAUTHORIZED",
+				},
+			});
+		});
+
+		it("handles forbidden error", async () => {
+			const app = createTestApp();
+			app.get("/test", () => {
+				throw Errors.forbidden("Access denied");
+			});
+
+			const res = await app.request("/test");
+			expect(res.status).toBe(403);
+			expect(await res.json()).toEqual({
+				error: {
+					message: "Access denied",
+					code: "FORBIDDEN",
+				},
+			});
+		});
+
+		it("handles notFound error", async () => {
+			const app = createTestApp();
+			app.get("/test", () => {
+				throw Errors.notFound("Resource not found");
+			});
+
+			const res = await app.request("/test");
+			expect(res.status).toBe(404);
+			expect(await res.json()).toEqual({
+				error: {
+					message: "Resource not found",
+					code: "NOT_FOUND",
+				},
+			});
+		});
+
+		it("handles conflict error", async () => {
+			const app = createTestApp();
+			app.get("/test", () => {
+				throw Errors.conflict("Already exists");
+			});
+
+			const res = await app.request("/test");
+			expect(res.status).toBe(409);
+			expect(await res.json()).toEqual({
+				error: {
+					message: "Already exists",
+					code: "CONFLICT",
+				},
+			});
+		});
+
+		it("handles validationError", async () => {
+			const app = createTestApp();
+			app.get("/test", () => {
+				throw Errors.validationError("Invalid data");
+			});
+
+			const res = await app.request("/test");
+			expect(res.status).toBe(422);
+			expect(await res.json()).toEqual({
+				error: {
+					message: "Invalid data",
+					code: "VALIDATION_ERROR",
+				},
+			});
+		});
+
+		it("handles internal error", async () => {
+			const app = createTestApp();
+			app.get("/test", () => {
+				throw Errors.internal("Database connection failed");
+			});
+
+			const res = await app.request("/test");
+			expect(res.status).toBe(500);
+			expect(await res.json()).toEqual({
+				error: {
+					message: "Database connection failed",
+					code: "INTERNAL_ERROR",
+				},
+			});
+		});
+	});
+
+	describe("unknown error handling", () => {
+		it("handles generic Error with 500 status", async () => {
+			const app = createTestApp();
+			app.get("/test", () => {
+				throw new Error("Unexpected error");
+			});
+
+			const res = await app.request("/test");
+			expect(res.status).toBe(500);
+			const body = (await res.json()) as { error: { code: string } };
+			expect(body.error.code).toBe("INTERNAL_ERROR");
+		});
+	});
+});