[Bug]: ArraySchema.unshift() not working as intended.

[maanex]

Bug description

Array.unshift should insert an item at the beginning of the array.
ArraySchema.unshift does the same, if the array has only been .push()'d to so far. As soon as either .pop() or .shift() was called on the ArraySchema, any .unshift() will mess the array up.

Example code below is also available on stackblitz.

import { ArraySchema } from '@colyseus/schema'
const x = new ArraySchema()
x.push(1)
x.push(2)
x.push(3)
x.push(4)
x.push(5)
x.pop()
x.pop()
x.push(9)
console.log(x.toArray()) // "[ 1, 2, 3, 9 ]"
x.unshift(8)
console.log(x.toArray())

// expected
"[ 8, 1, 2, 3, 9 ]"

// actual
"[ 8, 1, 2, 9, 3, 9 ]"

This example uses .pop() though a similar invalid state is reached if .pop() is replaced with .shift()

Optional: Minimal reproduction

https://stackblitz.com/edit/colyseus-schema-issue-report-iwe3ai?file=index.ts

[endel]

Thanks for sharing the reproduction scenario, will add this to colyseus/colyseus#641

[maanex]

Thank you, appreciate your work! Can you recommend a workaround for this until 3.0 is out that doesn't use .unshift() but still inserts an item at the front of the array? My only solution right now is to reverse() push() reverse() - which seems to work fine.

[endel]

As a workaround, you can try flushing the changes (via this.broadcastPatch()) to force the state to sync before doing the .unshift() operation:

x.push(1)
x.push(2)
x.push(3)
x.push(4)
x.push(5)
x.pop()
x.pop()
x.push(9)
this.broadcastPatch(); // HERE
x.unshift(8)

[maanex]

Will try, thank you!