Fails to raise error if a non-existent module is included in the config file

[andrewphilipsmith]

(This issue was originally opened here urbangrammarai#24)

How to reproduce

1. Run pyveg_generate_config to create a config file.
2. Edit the modules_to_use to include a module DoesNotExist. eg:

modules_to_use = {
    "Sentinel2": [
        "VegetationDownloader",
        "DoesNotExist"
    ]
}

3. Run pyvis_run_pipeline with the config file.

Expected behaviour

One or both of the following:

• An error message it included in the log file
• The pipeline execution is interrupted

Actual behaviour

The pipeline executes without any warnings or errors. The non-existent module is silently skipped.