* Use direct message handler functions
* Remove unused targetPopupId
* Make target a member of FrontendApiSender
* Rename frameId to parentFrameId for clarity
* Remove _parentFrameId
* Rename _parentId to _parentPopupId for clarity
* Mark functions as private
* Remove constructor side effects
* Use safer handler invocation
* Mark functions as private
* Mark fields as private
* Update BackendApiForwarder public API
* Create new logging methods on yomichan object
* Use new yomichan.logError instead of global logError
* Remove old logError
* Handle unhandledrejection events
* Add addEventListener stub
* Update log function
* Update error conversion to support more types
* Add log event
* Add API log function
* Log errors to the backend
* Make error/warning logs update the badge
* Clear log error indicator on extension button click
* Log correct URL on the background page
* Fix incorrect error conversion
* Remove unhandledrejection handling
Firefox doesn't support it properly.
* Remove unused argument type from log function
* Improve function name
* Change console.warn to yomichan.logWarning
* Move log forwarding initialization into main scripts
