Raise error when EWOKS_CONFIG_URI is provided but has a syntax error

[woutdenolf]

Celery configuration with syntax errors

#celeryconfig_sql.py
broker_url: f"sqla+sqlite:///celery.db"
result_backend: f"db+sqlite:///celery_results.db"

Start the worker

export EWOKS_CONFIG_URI=celeryconfig_sql.py
ewoksjob worker 

Fallback to rabbitmq without even mentioning the configuration

[2026-06-24 07:22:42,364: WARNING/MainProcess] No hostname was supplied. Reverting to default 'localhost'
 
...

[2026-06-24 07:22:43,019: ERROR/MainProcess] consumer: Cannot connect to amqp://guest:**@127.0.0.1:5672//: [Errno 111] Connection refused.
Trying again in 2.00 seconds... (1/100)

[2026-06-24 07:22:45,020: ERROR/MainProcess] consumer: Cannot connect to amqp://guest:**@127.0.0.1:5672//: [Errno 111] Connection refused.
Trying again in 4.00 seconds... (2/100)

[2026-06-24 07:22:49,022: ERROR/MainProcess] consumer: Cannot connect to amqp://guest:**@127.0.0.1:5672//: [Errno 111] Connection refused.
Trying again in 6.00 seconds... (3/100)

[woutdenolf]

In fact the example script is not a syntax error. So raise when no global variables are defined.