./gradlew metacatPorts fails with jq error

[Leotomas]

Hello dear metacat team,

I am trying to run metacat via docker, as explained in your project documentation but running ./gradlew metacatPorts yields the following error:

> Task :metacat-functional-tests:metacatPorts
jq: error (at <stdin>:263): Cannot iterate over null (null)

> Task :metacat-functional-tests:metacatPorts FAILED

FAILURE: Build failed with an exception.

* Where:
Build file '/home/XXXX/playground/metacat/metacat-functional-tests/build.gradle' line: 114

* What went wrong:
Execution failed for task ':metacat-functional-tests:metacatPorts'.
> Process 'command 'sh'' finished with non-zero exit value 10

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

Deprecated Gradle features were used in this build, making it incompatible with Gradle 7.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/6.8.3/userguide/command_line_interface.html#sec:command_line_warnings

BUILD FAILED in 35m 2s
93 actionable tasks: 51 executed, 42 up-to-date

Environment:

• Debian 10 Buster
• openjdk version "1.8.0_292"
• jq-1.5-1-a5b5cbe

Any pointers?