The jammy package autopkgtest suite has been failing, as shown in:
https://autopkgtest.ubuntu.com/packages/c/composer/jammy/amd64 (see errors below).
While this seems to be caused by changes related to the new PSR stack introduced in jammy, further investigation may be required.
There were 24 errors:
1) Composer\Test\Plugin\PluginInstallerTest::testInstallNewPlugin
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
2) Composer\Test\Plugin\PluginInstallerTest::testInstallPluginWithRootPackageHavingFilesAutoload
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
3) Composer\Test\Plugin\PluginInstallerTest::testInstallMultiplePlugins
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
4) Composer\Test\Plugin\PluginInstallerTest::testUpgradeWithNewClassName
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
5) Composer\Test\Plugin\PluginInstallerTest::testUninstall
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
6) Composer\Test\Plugin\PluginInstallerTest::testUpgradeWithSameClassName
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
7) Composer\Test\Plugin\PluginInstallerTest::testRegisterPluginOnlyOneTime
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
8) Composer\Test\Plugin\PluginInstallerTest::testStarPluginVersionWorksWithAnyAPIVersion
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
9) Composer\Test\Plugin\PluginInstallerTest::testPluginConstraintWorksOnlyWithCertainAPIVersion
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
10) Composer\Test\Plugin\PluginInstallerTest::testPluginRangeConstraintsWorkOnlyWithCertainAPIVersion
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
11) Composer\Test\Plugin\PluginInstallerTest::testCommandProviderCapability
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
12) Composer\Test\Plugin\PluginInstallerTest::testIncapablePluginIsCorrectlyDetected
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
13) Composer\Test\Plugin\PluginInstallerTest::testCapabilityImplementsComposerPluginApiClassAndIsConstructedWithArgs
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
14) Composer\Test\Plugin\PluginInstallerTest::testQueryingWithInvalidCapabilityClassNameThrows with data set #0 (null)
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
15) Composer\Test\Plugin\PluginInstallerTest::testQueryingWithInvalidCapabilityClassNameThrows with data set #1 ('')
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
16) Composer\Test\Plugin\PluginInstallerTest::testQueryingWithInvalidCapabilityClassNameThrows with data set #2 (0)
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
17) Composer\Test\Plugin\PluginInstallerTest::testQueryingWithInvalidCapabilityClassNameThrows with data set #3 (1000)
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
18) Composer\Test\Plugin\PluginInstallerTest::testQueryingWithInvalidCapabilityClassNameThrows with data set #4 (' ')
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
19) Composer\Test\Plugin\PluginInstallerTest::testQueryingWithInvalidCapabilityClassNameThrows with data set #5 (array(1))
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
20) Composer\Test\Plugin\PluginInstallerTest::testQueryingWithInvalidCapabilityClassNameThrows with data set #6 (array())
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
21) Composer\Test\Plugin\PluginInstallerTest::testQueryingWithInvalidCapabilityClassNameThrows with data set #7 (stdClass Object ())
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
22) Composer\Test\Plugin\PluginInstallerTest::testQueryingNonProvidedCapabilityReturnsNullSafely
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
23) Composer\Test\Plugin\PluginInstallerTest::testQueryingWithNonExistingOrWrongCapabilityClassTypesThrows with data set #0 ('\stdClass')
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
24) Composer\Test\Plugin\PluginInstallerTest::testQueryingWithNonExistingOrWrongCapabilityClassTypesThrows with data set #1 ('NonExistentClassLikeMiddleClass')
TypeError: array_merge(): Argument #1 must be of type array, bool given
/usr/share/php/Composer/Config.php:191
/tmp/autopkgtest.Wz3jaT/build.dP0/src/tests/Composer/Test/Plugin/PluginInstallerTest.php:120
