nl_tokens: Executes the currently registered database schema migration listeners with the provided arguments .
pl_tokens: function executeMigrationListeners ( databaseName , oldVersion , newVersion , completionPromise ) { for ( let listener of migrationListeners ) { <mask> { listener ( databaseName , oldVersion , newVersion , completionPromise ) } catch ( e ) { console . warn ( "A schema migration event listener threw an error" , e ) ; } } }