style: satisfy linter variable casing

[gavmor]

From what I can tell, Travis CI is failing for want of a particular variable casing:

167:17  error    Identifier 'alfa_beta_match' is not in camel case  @typescript-eslint/camelcase
168:15  error    Identifier 'alfa_beta_match' is not in camel case  @typescript-eslint/camelcase
168:34  error    Identifier 'alfa_beta_match' is not in camel case  @typescript-eslint/camelcase

Hopefully this change will permit Travis to complete its journey, and release the laudable v5.8.4 version which includes the bug-fixing commit from @rosselm.