error tracking in api endpoint

Understanding the Fetch API

The MDN documentation on using the Fetch API answers most of your questions, it's nicely written with many example use cases, I recommend to read it well from top to bottom.

Checking that the fetch was successful

Given this code:

const response = await fetch(URL, ...)
if (!response.ok) {
  // ...
}

The if statement will not be reached if fetch throws an exception, which can happen for example when the URL is garbage, or the server does not respond, or other kind of network errors.

The documentation has a dedicated section on error handling, and recommends to use this pattern:

fetch('flowers.jpg')
  .then((response) => {
    if (!response.ok) {
      throw new Error('Network response was not OK');
    }
    return response.blob();
  })
  .then((myBlob) => {
    myImage.src = URL.createObjectURL(myBlob);
  })
  .catch((error) => {
    console.error('There has been a problem with your fetch operation:', error);
  });

Behavior of finally and the return statement

The MDN documentation on Promises explains this nicely.

The block of code in finally will always be executed, whether the return statement is reached or an exception is thrown.

For example:

const result = await new Promise(resolve => resolve("success"))
  .finally(() => console.log("finally in case of success"))

console.log("result =", result)

await new Promise((resolve, reject) => reject(new Error("failure")))
  .catch(err => console.log("failure happened"))
  .finally(() => console.log("finally in case of failure"))

await new Promise((resolve, reject) => reject(new Error("failure")))
  .finally(() => console.log("finally in case of failure without catching"))

The output of the above code will be:

finally in case of success
result = success
failure happened
finally in case of failure
finally in case of failure without catching
file:///path/to/example.js:50
await new Promise((resolve, reject) => reject(new Error("failure")))
                                              ^

Error: failure
    at file:///path/to/example.js:50:47
    at new Promise (<anonymous>)
    at file:///path/to/example.js:50:7
    at processTicksAndRejections (node:internal/process/task_queues:94:5)

Setting error status, notifying the user

Where can I set the error status in my code to notify the user and my tracking to get insight on what went wrong.

Follow the example in the MDN docs:

• Chain the fetch to a .then(...), which checks the response.ok flag and returns response.json() if ok,
• Chain another .then(...), which will receive the json from the previous one, handle it, and notify the user of success.
• Chain a .catch(...) to handle exceptions that the previous calls may have thrown, for example about network errors, or when response.ok was not true. Notify the user of failure.
• Chain a .finally(...) to do cleanup that must always be performed, regardless of successful processing of the response or failures.