Invalid data type in config spammaster.schema

Thanks for reporting and for the patch cacrody,
I see the issue spammaster.schema.yml, your patch needed a few changes to reflect the type of field:

spammaster.settings_white:
  type: config_object
  mapping:
    white_key:
      type: textfield
      label: ''

We have launched version 1.88 that should fix the issue. Let us know if it works for you.

The new module version works perfectly, thank you very much