patch ``undefined`` over ``null`` type error

[franckdsf]

When creating a table with a null variable, it's possible to pass an undefined value to the patch function without TypeScript raising an error — even though this will crash at runtime.

export const test = defineTable({
  nullVariable: v.union(v.null(), v.string()),
  undefinedVariable: v.optional(v.string()),
})

await ctx.db.patch(testId, {
  nullVariable: undefined,   // <--------- no TypeScript error
  undefinedVariable: null    // <--------- TypeScript error
})

Expected behavior: TypeScript should warn that undefined is not a valid value for nullVariable.

[nipunn1313]

This seems reasonable!

I was able to repro this failing at runtime

just convex run simple:nipunntest
✖ Failed to run function "simple:nipunntest":
Error: [Request ID: b6e6f4f5179064a9] Server Error
Uncaught Error: Failed to insert or update a document in table "test" because it does not match the schema: Object is missing the required field `nullVariable`. Consider wrapping the field validator in `v.optional(...)` if this is expected.

Object: {}
Validator: v.object({nullVariable: v.union(v.null(), v.string()), undefinedVariable: v.optional(v.string())})
    at async handler (../convex/simple.ts:36:27)

so having it fail at compile time seems like a benefit.

If someone would like to give it a shot -

The logic for this is in here

https://github.com/get-convex/convex-backend/blob/main/npm-packages/convex/src/server/data_model.ts

with tests here

https://github.com/get-convex/convex-backend/blob/main/npm-packages/convex/src/server/database.test.ts

I am unlikely to have time to work on this - but we'll take help if someone wants to try and figure it out.