Fix AST spacing (#9366)

Fixes #9357

The main issue was the spread operator using at the wrong place in functions overriding spacing of nodes. The bug, to be visible, required copying AST node before, because during copying `whitespace` field was explicitly set to undefined (in opposite to being unset), what in turns make spread overriding the value set by those functions.

# Important Notes
* To enable VSCode debugging, added a workspace for vitest and fix any relative path to be working-dir independent.

app/gui2/shared/ast/ffi.ts

@@ -14,7 +14,10 @@ export function xxHash128(input: string) {
 export async function initializeFFI(path?: string | undefined) {
   if (isNode) {
     const fs = await import('node:fs/promises')
-    const buffer = fs.readFile(path ?? './rust-ffi/pkg/rust_ffi_bg.wasm')
+    const { fileURLToPath, URL: nodeURL } = await import('node:url')
+    const buffer = fs.readFile(
+      path ?? fileURLToPath(new nodeURL('../../rust-ffi/pkg/rust_ffi_bg.wasm', import.meta.url)),
+    )
     await init(buffer)
   } else {
     await init()

app/gui2/shared/ast/index.ts

@@ -26,7 +26,7 @@ export function asOwned<T>(t: T): Owned<T> {
   return t as Owned<T>
 }
 
-export type NodeChild<T> = { whitespace?: string | undefined; node: T }
+export type NodeChild<T> = { whitespace: string | undefined; node: T }
 export type RawNodeChild = NodeChild<AstId> | NodeChild<SyncTokenId>
 
 export function newExternalId(): ExternalId {

app/gui2/shared/ast/tree.ts

@@ -642,17 +642,20 @@ function ensureSpacedOnlyIf<T>(
 }
 function ensureSpaced<T>(child: NodeChild<T>, verbatim: boolean | undefined): NodeChild<T> {
   if (verbatim && child.whitespace != null) return child
-  return child.whitespace ? child : { whitespace: ' ', ...child }
+  return child.whitespace ? child : { ...child, whitespace: ' ' }
 }
 function ensureUnspaced<T>(child: NodeChild<T>, verbatim: boolean | undefined): NodeChild<T> {
   if (verbatim && child.whitespace != null) return child
-  return child.whitespace === '' ? child : { whitespace: '', ...child }
+  return child.whitespace === '' ? child : { ...child, whitespace: '' }
+}
+function preferSpacedIf<T>(child: NodeChild<T>, condition: boolean): NodeChild<T> {
+  return condition ? preferSpaced(child) : preferUnspaced(child)
 }
 function preferUnspaced<T>(child: NodeChild<T>): NodeChild<T> {
-  return child.whitespace === undefined ? { whitespace: '', ...child } : child
+  return child.whitespace === undefined ? { ...child, whitespace: '' } : child
 }
 function preferSpaced<T>(child: NodeChild<T>): NodeChild<T> {
-  return child.whitespace === undefined ? { whitespace: ' ', ...child } : child
+  return child.whitespace === undefined ? { ...child, whitespace: ' ' } : child
 }
 export class MutableApp extends App implements MutableAst {
   declare readonly module: MutableModule
@@ -1031,7 +1034,7 @@ function multiSegmentAppSegment<T extends MutableAst>(
   body: Owned<T> | undefined,
 ): MultiSegmentAppSegment<OwnedRefs> | undefined {
   return {
-    header: { node: Token.new(header, RawAst.Token.Type.Ident) },
+    header: autospaced(Token.new(header, RawAst.Token.Type.Ident)),
     body: spaced(body ? (body as any) : undefined),
   }
 }
@@ -1777,12 +1780,7 @@ export class Function extends Ast {
     yield name
     for (const def of argumentDefinitions) yield* def
     yield { whitespace: equals.whitespace ?? ' ', node: this.module.getToken(equals.node) }
-    if (body)
-      yield ensureSpacedOnlyIf(
-        body,
-        !(this.module.tryGet(body.node) instanceof BodyBlock),
-        verbatim,
-      )
+    if (body) yield preferSpacedIf(body, this.module.tryGet(body.node) instanceof BodyBlock)
   }
 }
 export class MutableFunction extends Function implements MutableAst {
@@ -2526,11 +2524,13 @@ function unspaced<T extends object | string>(node: T | undefined): NodeChild<T>
   return { whitespace: '', node }
 }
 
-function autospaced<T extends object | string>(node: T): NodeChild<T>
-function autospaced<T extends object | string>(node: T | undefined): NodeChild<T> | undefined
-function autospaced<T extends object | string>(node: T | undefined): NodeChild<T> | undefined {
+export function autospaced<T extends object | string>(node: T): NodeChild<T>
+export function autospaced<T extends object | string>(node: T | undefined): NodeChild<T> | undefined
+export function autospaced<T extends object | string>(
+  node: T | undefined,
+): NodeChild<T> | undefined {
   if (node === undefined) return node
-  return { node }
+  return { whitespace: undefined, node }
 }
 
 export interface Removed<T extends MutableAst> {

app/gui2/src/components/GraphEditor/collapsing.ts

@@ -1,7 +1,7 @@
 import { asNodeId, GraphDb, type NodeId } from '@/stores/graph/graphDatabase'
 import { assert, assertDefined } from '@/util/assert'
 import { Ast } from '@/util/ast'
-import { isIdentifier, moduleMethodNames, type Identifier } from '@/util/ast/abstract'
+import { autospaced, isIdentifier, moduleMethodNames, type Identifier } from '@/util/ast/abstract'
 import { nodeFromAst } from '@/util/ast/node'
 import { unwrap } from '@/util/data/result'
 import {
@@ -185,7 +185,7 @@ export function performCollapse(
       if (astIdsToExtract.has(ast.id)) {
         collapsed.push(ast)
         if (ast.id === astIdToReplace) {
-          refactored.push({ expression: { node: refactoredAst } })
+          refactored.push({ expression: autospaced(refactoredAst) })
         }
       } else {
         refactored.push(line)