'Extract type' from property signature with erroneous initializer causes assertion failure

[DanielRosenwasser]

type Foo = [|{
    x: string = someString;
}|]

Request an "extract to type alias" refactoring on the specified [|range|]:

 Debug Failure. False expression: Token end is child end
Error: Debug Failure. False expression: Token end is child end
    at processChildNode (typescript/lib/tsserver.js:165873:17)
    at typescript/lib/tsserver.js:165804:9
    at visitNode2 (typescript/lib/tsserver.js:29284:18)
    at forEachChildInPropertySignature (typescript/lib/tsserver.js:29340:167)
    at forEachChild (typescript/lib/tsserver.js:29798:35)
    at processNode (typescript/lib/tsserver.js:165801:5)
    at processChildNode (typescript/lib/tsserver.js:165880:7)
    at processChildNodes (typescript/lib/tsserver.js:165923:32)
    at typescript/lib/tsserver.js:165817:9
    at visitNodes (typescript/lib/tsserver.js:29289:14)
    at forEachChildInTypeLiteral (typescript/lib/tsserver.js:29399:12)
    at forEachChild (typescript/lib/tsserver.js:29798:35)
    at processNode (typescript/lib/tsserver.js:165801:5)
    at processChildNode (typescript/lib/tsserver.js:165880:7)
    at typescript/lib/tsserver.js:165804:9
    at visitNode2 (typescript/lib/tsserver.js:29284:18)
    at forEachChildInTypeAliasDeclaration (typescript/lib/tsserver.js:29575:144)
    at forEachChild (typescript/lib/tsserver.js:29798:35)
    at processNode (typescript/lib/tsserver.js:165801:5)
    at formatSpanWorker (typescript/lib/tsserver.js:165609:5)
    at typescript/lib/tsserver.js:165549:105
    at getFormattingScanner (typescript/lib/tsserver.js:164365:15)
    at Object.formatNodeGivenIndentation (typescript/lib/tsserver.js:165549:10)
    at getFormattedTextOfNode (typescript/lib/tsserver.js:163762:43)
    at format (typescript/lib/tsserver.js:163742:27)
    at computeNewText (typescript/lib/tsserver.js:163743:219)
    at typescript/lib/tsserver.js:163704:25
    at mapDefined (typescript/lib/tsserver.js:2627:22)
    at typescript/lib/tsserver.js:163702:28
    at mapDefined (typescript/lib/tsserver.js:2627:22)
    at Object.getTextChangesFromChanges (typescript/lib/tsserver.js:163696:12)
    at ChangeTracker.getChanges (typescript/lib/tsserver.js:163585:35)
    at ChangeTracker.with (typescript/lib/tsserver.js:163083:20)
    at Object.getRefactorEditsToExtractType [as getEditsForAction] (typescript/lib/tsserver.js:156988:60)
    at Object.getEditsForRefactor (typescript/lib/tsserver.js:156469:31)
    at Object.getEditsForRefactor2 [as getEditsForRefactor] (typescript/lib/tsserver.js:135592:32)
    at IpcIOSession.getEditsForRefactor (typescript/lib/tsserver.js:178779:49)
    at getEditsForRefactor (typescript/lib/tsserver.js:177034:43)

[DanielRosenwasser]

As usual, this has to do with the visitor with visitEachChild not actually visiting the initializer property on PropertySignatures, even though forEachChild does.

And as usual, it's awkward because updatePropertySignature doesn't give control over it. It really should either drop the property signature entirely or provide a mechanism to update it. I'd probably lean towards the latter

[rbuckton]

initializer on a property signature is a grammar error and isn't part of a syntactically valid AST. Supporting it in visitEachChild would require adding it to the updatePropertySignature factory method, which I'm not a fan of. I may look into an alternate approach, as I'd eventually like to find a way to remove these grammar-error-only node properties from nodes to reduce memory overhead.

[rbuckton]

I don't think the issue is with visitEachChild, since new positions are assigned by the printer via a TextChangesWriter.

[rbuckton]

I don't think the issue is with visitEachChild, since new positions are assigned by the printer via a TextChangesWriter.

Ah, never mind. Both the emitter and visitEachChild need to be fixed for this to work.