[janedbal]

php-code-coverage stores null for a dead (unreachable) line in .cov files. PhpUnitCoverageExtractor accepts only arrays, so it throws on null. Every command that reads .cov (check, patch-coverage, merge, convert) then stops with an internal error.

One dead line in the coverage scope is enough. Example from a real PHPUnit 13 + Xdebug run:

switch ($a) {
    case 'x':
        return 1;
        break;    // dead line
}

Dead.php => {"10":[],"11":[],"12":null,"14":[]}

‼️  Internal error: LogicException: Invalid coverage file: 'dead3.cov'. Expected array under Dead.php and #12, got null

The null comes in two cases. If no test runs the file, php-code-coverage finds dead lines by static analysis. If a test runs the file, Xdebug reports the line as dead.

Now the extractor skips null lines, as the PHPUnit Clover and Cobertura reports do. A dead line is not executable, so no rule can require its coverage.

• New test with a null line. It fails on master.

Co-Authored-By: Claude Code