shell: add timeout logic and rework error handling

what's important:

* if task code ran, it exits with 0. this code is regardless of (error, result)
  * when it exited cleanly, we will get the values from the database

* if task timed out, the box code kills it and it has a flag tracking timedOut. we can
  ignore exit code in this case.

* if task code was stopped, box code will send SIGTERM which ideally it will handle and end with 70.

* if task code crashed and it caught the exception, it will return 50

* if task code crashed and node nuked us, it will exit with 1

* if task code was killed with some unhandleabe signal, taskworker.sh will return the signal (9=SIGKILL)

src/routes/test/tasks-test.js

@@ -31,7 +31,6 @@ describe('Tasks API', function () {
         expect(response.body.active).to.be(false); // finished
         expect(response.body.success).to.be(true);
         expect(response.body.result).to.be('ping');
-        expect(response.body.completed).to.be(true);
         expect(response.body.error).to.be(null);
     });
 
@@ -63,7 +62,9 @@ describe('Tasks API', function () {
 
         setTimeout(async function () {
             const response = await superagent.post(`${serverUrl}/api/v1/tasks/${taskId}/stop`)
-                .query({ access_token: owner.token });
+                .query({ access_token: owner.token })
+                .send({})
+                .ok(() => true);
 
             expect(response.status).to.equal(204);
         }, 100);
@@ -77,7 +78,6 @@ describe('Tasks API', function () {
         expect(response.body.active).to.be(false); // finished
         expect(response.body.success).to.be(false);
         expect(response.body.result).to.be(null);
-        expect(response.body.completed).to.be(true);
         expect(response.body.error.message).to.contain('stopped');
     });
 
@@ -96,7 +96,6 @@ describe('Tasks API', function () {
         expect(response.body.tasks[0].active).to.be(false); // finished
         expect(response.body.tasks[0].success).to.be(true); // finished
         expect(response.body.tasks[0].result).to.be('ping');
-        expect(response.body.tasks[0].completed).to.be(true);
         expect(response.body.tasks[0].error).to.be(null);
     });
 });