fix: prevent crash when v8 incorrectly merges static_initializer's

[AriPerkkio]

Fixes vitest-dev/vitest#5329.

Reproduction:

ari ~/Git/reproductions (v8-merge) $ cat package.json 
{
  "name": "reproductions",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "scripts": {},
  "license": "MIT",
  "devDependencies": {
    "@bcoe/v8-coverage": "^0.2.3",
    "@types/node": "^20.11.24"
  }
}
ari ~/Git/reproductions (v8-merge) $ node -v; npm -v
v20.11.1
10.2.4

import { mergeProcessCovs } from "@bcoe/v8-coverage";
import { writeFileSync } from "node:fs";
import inspector from "node:inspector";

writeFileSync(
  "./source-file.js",
  `
export class Foo {
  static First = true ? 1 : 0;
  static Seoncd = 1;
}
`.trim(),
  "utf8"
);

const session = new inspector.Session();

session.connect();
session.post("Profiler.enable");
session.post("Profiler.startPreciseCoverage", {
  callCount: true,
  detailed: true,
});

await import("./source-file.js");

const coverage = await collectCoverage("source-file.js");
console.log(JSON.stringify(coverage, null, 2));

mergeProcessCovs([coverage]);

async function collectCoverage(filename) {
  return new Promise((resolve, reject) => {
    session.post("Profiler.takePreciseCoverage", async (error, coverage) => {
      if (error) return reject(error);

      const result = coverage.result.filter((entry) =>
        entry.url.includes(filename)
      );

      resolve({ result });
    });
  });
}

ari ~/Git/reproductions (v8-merge) $ node index.mjs 
{
  "result": [
    {
      "scriptId": "139",
      "url": "file:///rootdirs/reproductions/source-file.js",
      "functions": [
        {
          "functionName": "",
          "ranges": [
            {
              "startOffset": 0,
              "endOffset": 72,
              "count": 1
            }
          ],
          "isBlockCoverage": true
        },
        {
          "functionName": "<static_initializer>",
          "ranges": [
            {
              "startOffset": 52,
              "endOffset": 69,
              "count": 1
            },
            {
              "startOffset": 45,
              "endOffset": 48,
              "count": 0
            }
          ],
          "isBlockCoverage": true
        }
      ]
    }
  ]
}
/rootdirs/reproductions/node_modules/@bcoe/v8-coverage/dist/lib/range-tree.js:27
                [parent, parentCount] = stack[stack.length - 1];
                                      ^

TypeError: undefined is not iterable (cannot read property Symbol(Symbol.iterator))
    at RangeTree.fromSortedRanges (/rootdirs/reproductions/node_modules/@bcoe/v8-coverage/dist/lib/range-tree.js:27:39)
    at normalizeFunctionCov (/rootdirs/reproductions/node_modules/@bcoe/v8-coverage/dist/lib/normalize.js:74:41)
    at Object.deepNormalizeScriptCov (/rootdirs/reproductions/node_modules/@bcoe/v8-coverage/dist/lib/normalize.js:59:9)
    at mergeScriptCovs (/rootdirs/reproductions/node_modules/@bcoe/v8-coverage/dist/lib/merge.js:59:21)
    at mergeProcessCovs (/rootdirs/reproductions/node_modules/@bcoe/v8-coverage/dist/lib/merge.js:34:21)
    at file:///rootdirs/reproductions/index.mjs:30:1

Node.js v20.11.1

[sagupta1001]

@AriPerkkio @bcoe would it be possible to merge this PR?

[ebrpol]

I'd also greatly appreciate it if this MR could be merged

[AriPerkkio]

If you are running into this issue, try upgrading your Node to latest version. Looks like there has been some fixes related to V8 coverage reporting.

[ebrpol]

If you are running into this issue, try upgrading your Node to latest version. Looks like there has been some fixes related to V8 coverage reporting.

Thanks for the heads up!

Would it be possible to merge this MR nonetheless? I am working on a large project on Node 18, in which it's very costly to upgrade to Node 20.

[ebrpol]

I've tested on Node 20.12.2 and it still has the same issue. Node 22.1.0 does not have this issue indeed!

I think a lot of people will still be on an LTS version, so I think it will be helpful if this MR can be merged.