Fixes appearing RuntimeError in __app_data_by_key that appears when the function
looks for "crypto-key" or "encryption" in broken FCM messages. These messages are
skipped when the field is not found.
See https://github.com/MatthieuLemoine/push-receiver/issues/21
Also fixes a mutable function parameter, replacing "[]" with None and a check.
Fixes appearing RuntimeError in __app_data_by_key that appears when the function looks for "crypto-key" or "encryption" in broken FCM messages. These messages are skipped when the field is not found. See https://github.com/MatthieuLemoine/push-receiver/issues/21
Also fixes a mutable function parameter, replacing "[]" with None and a check.
Increases patch version.