c8 fails with undefined is not iterable error

[jasonpolites]

• Version: v20.12.2
• Platform: Ubuntu 20.04.6 LTS (actually WSL, but the uname output is mostly useless)

I'm trying to replace nyc due to this bug, but out of the box c8 seems to fail with the following error:

TypeError: undefined is not iterable (cannot read property Symbol(Symbol.iterator))
    at RangeTree.fromSortedRanges (<REDACTED>/node_modules/@bcoe/v8-coverage/dist/lib/range-tree.js:27:39)
    at normalizeFunctionCov (<REDACTED>/node_modules/@bcoe/v8-coverage/dist/lib/normalize.js:74:41)
    at Object.deepNormalizeScriptCov (<REDACTED>/node_modules/@bcoe/v8-coverage/dist/lib/normalize.js:59:9)
    at mergeScriptCovs (<REDACTED>/node_modules/@bcoe/v8-coverage/dist/lib/merge.js:59:21)
    at mergeProcessCovs (<REDACTED>/node_modules/@bcoe/v8-coverage/dist/lib/merge.js:34:21)
    at Report._getMergedProcessCov (<REDACTED>/node_modules/c8/lib/report.js:336:12)
    at Report.getCoverageMapFromAllCoverageFiles (<REDACTED>/node_modules/c8/lib/report.js:245:27)
    at Report.run (<REDACTED>/node_modules/c8/lib/report.js:84:31)
    at exports.outputReport (<REDACTED>/node_modules/c8/lib/commands/report.js:42:16)
    at <REDACTED>/node_modules/c8/bin/c8.js:30:15

My npm script command is:

"coverage": "c8 --reporter=html --reporter=text mocha"

I'm not sure what else I can provide, or where to look next 🤷‍♂️

[jasonpolites]

Issue also found here: vitest-dev/vitest#5329, corresponding to this PR: bcoe/v8-coverage#2