Pseudonymizer late error on non existing regexmapping

[ekneg54]

check with:

1. create pipeline.yml

input:
  dummy:
    type: dummy_input
    documents: [{ "foo": "bar" }]
output:
  dummy:
    type: dummy_output
pipeline:
  - pseudonymizername:
      type: pseudonymizer
      specific_rules:
        - filter: foo
          pseudonymizer:
            mapping:
              foo: DOES_NOT_EXIST
      generic_rules: []
      outputs:
        - dummy: pseudonyms_topic
      pubkey_analyst: analyst.crt
      pubkey_depseudo: depseudo.crt
      hash_salt: secret_salt
      regex_mapping: tests/testdata/unit/pseudonymizer/pseudonymizer_regex_mapping.yml
      max_cached_pseudonyms: 1000000

2. create needed pseudo keys

logprep pseudo generate -f analyst 1024
logprep pseudo generate -f depseudo 2048

run logprep with:

logprep run ./pipeline.yml

you will get nice error output complaining the regex mapping is not found