fix: invalid file request not properly handled; this fixes a security vulnerability in which an invalid file request can crash the server ([GHSA-xw6g-jjvf-wwf9](https://github.com/parse-community/parse-server/security/advisories/GHSA-xw6g-jjvf-wwf9)) (#8059)

spec/ParseFile.spec.js

@@ -623,6 +623,44 @@ describe('Parse.File testing', () => {
     });
   });
 
+  describe('getting files', () => {
+    it('does not crash on file request with invalid app ID', async () => {
+      const res1 = await request({
+        url: 'http://localhost:8378/1/files/invalid-id/invalid-file.txt',
+      }).catch(e => e);
+      expect(res1.status).toBe(403);
+      expect(res1.data).toEqual({ code: 119, error: 'Invalid application ID.' });
+      // Ensure server did not crash
+      const res2 = await request({ url: 'http://localhost:8378/1/health' });
+      expect(res2.status).toEqual(200);
+      expect(res2.data).toEqual({ status: 'ok' });
+    });
+
+    it('does not crash on file request with invalid path', async () => {
+      const res1 = await request({
+        url: 'http://localhost:8378/1/files/invalid-id//invalid-path/%20/invalid-file.txt',
+      }).catch(e => e);
+      expect(res1.status).toBe(403);
+      expect(res1.data).toEqual({ error: 'unauthorized' });
+      // Ensure server did not crash
+      const res2 = await request({ url: 'http://localhost:8378/1/health' });
+      expect(res2.status).toEqual(200);
+      expect(res2.data).toEqual({ status: 'ok' });
+    });
+
+    it('does not crash on file metadata request with invalid app ID', async () => {
+      const res1 = await request({
+        url: `http://localhost:8378/1/files/invalid-id/metadata/invalid-file.txt`,
+      });
+      expect(res1.status).toBe(200);
+      expect(res1.data).toEqual({});
+      // Ensure server did not crash
+      const res2 = await request({ url: 'http://localhost:8378/1/health' });
+      expect(res2.status).toEqual(200);
+      expect(res2.data).toEqual({ status: 'ok' });
+    });
+  });
+
   xdescribe('Gridstore Range tests', () => {
     it('supports range requests', done => {
       const headers = {