Uncaught exception when fetch API rejects

[milesnash]

This issue is closely related to #1203 in terms of how it manifests for consumers of client libs that in turn use this lib for making requests. However, its source is in a close-but-separate area of the code.

Consider the following code:

import { DisksClient } from '@google-cloud/compute';

const client = new DisksClient();
const project = 'my-project';
const zone = 'us-east1';

try {
  const [disks] = await client.list({
    project,
    zone
  });
} catch (err) {
  console.error(err);
}

I expected to land in the catch block in the case of transient network errors such as ETIMEDOUT. However, my program still errors with the following:

{
    "errorType": "Runtime.UnhandledPromiseRejection",
    "errorMessage": "FetchError: request to https://compute.googleapis.com:443/compute/v1/projects/my-project/regions/us-east1/disks? failed, reason: connect ETIMEDOUT [REDACTED IP ADDR]:443",
    "reason": {
        "errorType": "FetchError",
        "errorMessage": "request to https://compute.googleapis.com:443/compute/v1/projects/my-project/regions/us-east1/disks? failed, reason: connect ETIMEDOUT [REDACTED IP ADDR]:443",
        "code": "ETIMEDOUT",
        "message": "request to https://compute.googleapis.com:443/compute/v1/projects/my-project/regions/us-east1/disks? failed, reason: connect ETIMEDOUT [REDACTED IP ADDR]:443",
        "type": "system",
        "errno": "ETIMEDOUT",
        "stack": [
            "FetchError: request to https://compute.googleapis.com:443/compute/v1/projects/my-project/regions/us-east1/disks? failed, reason: connect ETIMEDOUT [REDACTED IP ADDR]:443",
            "    at ClientRequest.<anonymous> (/var/task/node_modules/node-fetch/lib/index.js:1461:11)",
            "    at ClientRequest.emit (events.js:400:28)",
            "    at ClientRequest.emit (domain.js:475:12)",
            "    at TLSSocket.socketErrorListener (_http_client.js:475:9)",
            "    at TLSSocket.emit (events.js:400:28)",
            "    at TLSSocket.emit (domain.js:475:12)",
            "    at emitErrorNT (internal/streams/destroy.js:106:8)",
            "    at emitErrorCloseNT (internal/streams/destroy.js:74:3)",
            "    at processTicksAndRejections (internal/process/task_queues.js:82:21)"
        ]
    },
    "promise": {},
    "stack": [
        "Runtime.UnhandledPromiseRejection: FetchError: request to https://compute.googleapis.com:443/compute/v1/projects/my-project/regions/us-east1/disks? failed, reason: connect ETIMEDOUT [REDACTED IP ADDR]:443",
        "    at process.<anonymous> (/var/runtime/index.js:35:15)",
        "    at process.emit (events.js:400:28)",
        "    at process.emit (/var/task/src/functions/runner/exec/handler.js:623206:21)",
        "    at processPromiseRejections (internal/process/promises.js:245:33)",
        "    at processTicksAndRejections (internal/process/task_queues.js:96:32)"
    ]
}

The fetch error message in this example is generated in node-fetch here. The fetch() Web API would also reject in such circumstances as described here.

I believe that consumers of such client libs would want to handle these errors in the way I have shown above and as described in #1203.