Incomplete data model validation: strings are accepted in the list of dimensions in a pre-aggregation definition

[igorlukanin]

Describe the bug
In JavaScript-based data models, strings are accepted in the list of dimensions in a pre-aggregation definition. This data model compiles but fails at runtime, when the query comes.

Removing the backticks around w_merchant_id fixes it:

        dimensions: [
          `w_merchant_id`
        ],

To Reproduce
Steps to reproduce the behavior:

1. Use the following data model.
2. Run a query.

{
  "dimensions": [
    "my_stores.account_id"
  ],
  "order": {
    "my_stores.account_id": "asc"
  }
}

3. See the error.

Typepath.join is not a function
TypeError: path.join is not a function
    at CubeEvaluator.byPathAnyType (/cube/node_modules/@cubejs-backend/schema-compiler/src/compiler/CubeEvaluator.ts:356:55)
    at CubeEvaluator.parsePathAnyType (/cube/node_modules/@cubejs-backend/schema-compiler/src/compiler/CubeEvaluator.ts:392:10)
    at /cube/node_modules/@cubejs-backend/schema-compiler/src/adapter/PreAggregations.js:909:75
    at Array.map (<anonymous>)
    at PreAggregations.cubesFromPreAggregation (/cube/node_modules/@cubejs-backend/schema-compiler/src/adapter/PreAggregations.js:909:41)
...

Expected behavior
This data model should fail at compile time with a clear error message.

Minimally reproducible Cube Schema

cube(`my_orders`, {
    sql_table: `public.my_orders`,
    dimensions: {
      w_merchant_id: {
        sql: `w_merchant_id`,
        type: `number`,
        primary_key: true, 
        public: true,
      },
    },
    pre_aggregations: {
      orders_rollup: {
        type: `rollup`, 
        dimensions: [
          `w_merchant_id`
        ],
    },
  }});
cube(`my_stores`, 
  {
    sql_table: `public.my_stores`,
    dimensions: {
      account_id: {
        sql: `account_id`,
        type: `string`,
      },
    },
    joins: {
      my_orders: {
        sql: `${account_id} = ${my_orders.w_merchant_id}`,
        relationship: `one_to_many`,
      }
    },
    pre_aggregations: {
      stores_rollup: {
        type: `rollup`,
        dimensions: [
          account_id, 
        ],
      },
      combined_rollup: {
        type: `rollup_join`,
        dimensions: [
          account_id,
          my_orders.w_merchant_id,
        ],
        rollups: [
          my_orders.orders_rollup, 
          stores_rollup
        ]
      },
    },
  }
);

Version:
v1.1.16

Additional context
Reported by Embeddable in Slack: https://cube-js.slack.com/archives/C04KDTE2EF7/p1737652681703019

[igorlukanin]

Discussed with @KSDaemon: this is actually quite tricky to fix. Since this is not a big deal, we can probably live with this.