Deno cotton 'must have type' - deno

Question

I'm following a course on Deno and Angular but I am stuck. I have even downloaded the final code supplied by the person who created the course and get the same type of error.
When I try and run this commmand: deno run --allow-net --unstable app.ts
I keep getting this error message:
Check file:///?:/????/deno-admin-main/app.ts
error: Uncaught Error: Column 'role_id' must have a type!
throw new Error(Column '${propertyKey}' must have a type!);
^
at https://deno.land/x/cotton#v0.7.5/src/model.ts:76:13
at DecorateProperty (https://deno.land/x/cotton#v0.7.5/src/utils>/reflect.ts:1431:27)
at Reflect.decorate (https://deno.land/x/cotton#v0.7.5/src/utils/reflect.ts:858:16)
at __decorate (file:///?:/????/deno-admin-main/src/models/role-permission.ts:3:92)
at file:///?:/????/deno-admin-main/src/models/role-permission.ts:9:5
// role-permission
import {Model, Primary, Column} from "https://deno.land/x/cotton#v0.7.5/mod.ts";
#Model('role_permissions')
export class RolePermission {
#Primary()
id!: number;
#Column()
role_id!: number;
#Column()
permission_id!: number;
}

Answer 1

According to their docs the use of this cotton feature requires a custom tsconfig.json to be included when running the program:
Keep in mind that this feature requires a custom TypeScript configuration to tell Deno that we want to use TypeScript decorators (opens new window), which is currently still an experimental feature.
// tsconfig.json
{
"compilerOptions": {
"experimentalDecorators": true,
"emitDecoratorMetadata": true
}
}
deno run --unstable --config ./tsconfig.json app.ts

Answer 2

The problem was a typo. I did not add "app.ts" to the file scripts.json:
{
"$schema": "https://deno.land/x/denon#2.4.7/schema.json",
"scripts": {
"start": {
"cmd": "deno run app.ts",
"desc": "run my app.ts file",
"allow": [
"net"
] ,
"tsconfig": "tsconfig.json"
}
},
"watcher": {
"match": [
"app.ts",
"src/**/*.ts"
]
}
}