the complete error:

(node:479) UnhandledPromiseRejectionWarning: TypeError: this.client.db.get is not a function
at GuildExt.get (/home/runner/Central-Discord-Anti/structures/Guild.js:16:35)
at GuildExt.get prefix [as prefix] (/home/runner/Central-Discord-Anti/structures/Guild.js:12:25)
at CommandHandler.prefix (/home/runner/Central-Discord-Anti/core/client.js:15:62)
at CommandHandler.parseCommand (/home/runner/Central-Discord-Anti/node_modules/discord-akairo/src/struct/commands/CommandHandler.js:770:65)
at CommandHandler.handle (/home/runner/Central-Discord-Anti/node_modules/discord-akairo/src/struct/commands/CommandHandler.js:361:37)
at processTicksAndRejections (internal/process/task_queues.js:97:5)
(node:479) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag --unhandled-rejections=strict (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 10)

someone help