test(error): add unit tests

test/error.ts

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+import * as chai from "chai";
+import * as sinon from "sinon";
+
+import { onUncaughtException, onUnhandledRejection } from "../src/error";
+
+describe("error", () => {
+    let sandbox: sinon.SinonSandbox;
+
+    beforeEach(() => (sandbox = sinon.createSandbox()));
+    afterEach(() => sandbox.restore());
+
+    it("should print an error for an exception", () => {
+        // Given
+        const consoleErrorStub = sandbox.stub(console, "error");
+        const processExitStub = sandbox.stub(process, "exit");
+
+        const error = new SyntaxError(
+            "Invalid regular expression: /^(feat)(((?scope>.*)))?(?<breaking>!)?: (?<description>.*)/: Invalid group",
+        );
+
+        // When
+        onUncaughtException(error);
+
+        // Then
+        chai.expect(consoleErrorStub).to.have.been.calledWith(
+            "An unknown error occurred. Failed to generate Markdown report.",
+        );
+        chai.expect(processExitStub).to.have.been.calledWith(1);
+    });
+
+    it("should print an error for a unhandled rejection", () => {
+        // Given
+        const consoleErrorStub = sandbox.stub(console, "error");
+        const processExitStub = sandbox.stub(process, "exit");
+
+        const error = new SyntaxError(
+            "Invalid regular expression: /^(feat)(((?scope>.*)))?(?<breaking>!)?: (?<description>.*)/: Invalid group",
+        );
+        const promise = Promise.reject();
+
+        // When
+        onUnhandledRejection(error, promise);
+
+        // Then
+        chai.expect(consoleErrorStub).to.have.been.calledWith(
+            "An unknown error occurred. Failed to generate Markdown report.",
+        );
+        chai.expect(processExitStub).to.have.been.calledWith(1);
+    });
+});