Cannot read property 'decl' of undefined while merge json reports

[storenth]

1. Jest instrument sources and produce .json reporter
2. Then I collect coverage with babel-plugin-istanbul and get second .json report
3. When I merge it with istanbul-merge I get the issue,

Looks like Jest instrument sources included import/export statements but babel-plugin-istanbul import/export statements are ignored (see screenshot: Jest on the left side and babel-plugin-istanbul on the right):

My dependencies:

    "babel-plugin-istanbul": "^4.1.6",
    "jest": "22.4.4",
    "babel-core": "6.26.3",
    "babel-eslint": "8.2.3",
    "babel-jest": "22.4.4",
    "babel-loader": "7.1.4",

[ljharb]

hmm - the error is coming from istanbul-reports, which this package doesn't use. Is it possible that you're using the output of istanbul-merge to generate an HTML report, and that's where the error is coming from?

[storenth]

@ljharb I don't sure I correctly got your question. I am using the next merge-report-flow:

    "merge": "istanbul-merge --out .nyc_output/out.json unit_coverage/coverage-unit.json raw_coverage/coverage-ui.json",
    "coverage": "nyc report --reporter=lcov --exclude-after-remap=false"

coverage-unit.json from Jest with .json reporter and coverage-ui.json saved from browser window.__coverage__ while UI-test automation.
Also, I have activity under istanbuljs/babel-plugin-istanbul/issues/129 and istanbuljs/babel-plugin-istanbul/issues/135