"invalid memory address or nil pointer dereference"

[cmdcolin]

Hello,
I found an error from running tsgo. I am not exactly sure what file caused it but I believe it's reproducible. it's a large-ish open source project here.

Repro

git clone git@github.com:GMOD/jbrowse-components
cd jbrowse-components
git clone tsgo_error_repro #branch to checkout with tsgo
yarn
yarn tsgo

Environment

running on node 24.1.0, ubuntu 24

"@typescript/native-preview": "^7.0.0-dev.20250612.1",

Log

❯❯❯ y tsgo
yarn run v1.22.22
$ /home/cdiesh/src/jbrowse-components/node_modules/.bin/tsgo
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x6f32b2]

goroutine 10700 [running]:
github.com/microsoft/typescript-go/internal/ast.IsBlock(...)
        github.com/microsoft/typescript-go/internal/ast/ast.go:3078
github.com/microsoft/typescript-go/internal/printer.(*Printer).emitConciseBody(0xc0fa3d6600?, 0xcea298?)
        github.com/microsoft/typescript-go/internal/printer/printer.go:2570 +0x12
github.com/microsoft/typescript-go/internal/printer.(*Printer).emitArrowFunction(0xc0fa3d6600, 0xc0f94497c0)
        github.com/microsoft/typescript-go/internal/printer/printer.go:2593 +0x20c
github.com/microsoft/typescript-go/internal/printer.(*Printer).emitExpression(0xc0fa3d6600, 0xc0f94497c0, 0x2)
        github.com/microsoft/typescript-go/internal/printer/printer.go:3030 +0x5a9
github.com/microsoft/typescript-go/internal/printer.(*Printer).emitInitializer(0xc0fa3d6600, 0xc0f94497c0, 0x7fc, 0xc0fad32fc0)
        github.com/microsoft/typescript-go/internal/printer/printer.go:1480 +0xa6
github.com/microsoft/typescript-go/internal/printer.(*Printer).emitCommonJSExport(0xc0fa3d6600, 0xc0fad32fc0)
        github.com/microsoft/typescript-go/internal/printer/printer.go:3760 +0x134
github.com/microsoft/typescript-go/internal/printer.(*Printer).emitStatement(0x76b0b5774248?, 0xc0f4fab860?)
        github.com/microsoft/typescript-go/internal/printer/printer.go:3967 +0x46f
github.com/microsoft/typescript-go/internal/printer.(*Printer).emitListItems(0xc0fa3d6600, 0xc00ef0, 0xc0fa3cc508, {0xc0fad50ae0, 0x2, 0x20?}, 0x1, 0x0, {0x0, 0xb08})
        github.com/microsoft/typescript-go/internal/printer/printer.go:4676 +0x4b9
github.com/microsoft/typescript-go/internal/printer.(*Printer).emitListRange(0xc0fa3d6600, 0xc00ef0, 0xc0fa3cc508, 0xc0fad358a0, 0x1, 0xaca940?, 0xc00616c788?)
        github.com/microsoft/typescript-go/internal/printer/printer.go:4473 +0x395
github.com/microsoft/typescript-go/internal/printer.(*Printer).emitSourceFile(0xc0fa3d6600, 0xc0fa3cc508)
        github.com/microsoft/typescript-go/internal/printer/printer.go:4395 +0x208
github.com/microsoft/typescript-go/internal/printer.(*Printer).Write(0xc0fa3d6600, 0xc0fa3cc508, 0xc0f7076fc0?, {0xd04590, 0xc0f4081e30}, 0x1?)
        github.com/microsoft/typescript-go/internal/printer/printer.go:4925 +0x100c
github.com/microsoft/typescript-go/internal/compiler.(*emitter).printSourceFile(0xc0f4c7fc20, {0xc0132a8b80, 0x74}, {0x0, 0x0}, 0xc0fa3cc508, 0xc0fa3d6600, 0x0)
        github.com/microsoft/typescript-go/internal/compiler/emitter.go:158 +0x289
github.com/microsoft/typescript-go/internal/compiler.(*emitter).emitDeclarationFile(0xc0f4c7fc20, 0xc00616c788, {0xc0132a8b80, 0x74}, {0x0, 0x0})
        github.com/microsoft/typescript-go/internal/compiler/emitter.go:127 +0x5c5
github.com/microsoft/typescript-go/internal/compiler.(*emitter).emit(0xc0f4c7fc20)
        github.com/microsoft/typescript-go/internal/compiler/emitter.go:43 +0x5d
github.com/microsoft/typescript-go/internal/compiler.(*Program).Emit.func2()
        github.com/microsoft/typescript-go/internal/compiler/program.go:762 +0x149
github.com/microsoft/typescript-go/internal/core.(*parallelWorkGroup).Queue.func1()
        github.com/microsoft/typescript-go/internal/core/workgroup.go:39 +0x50
created by github.com/microsoft/typescript-go/internal/core.(*parallelWorkGroup).Queue in goroutine 1
        github.com/microsoft/typescript-go/internal/core/workgroup.go:37 +0x85
error Command failed with exit code 2.

Maybe related

Saw this issue, somewhat similar error #898

[cmdcolin]

(note that I am not sure if it ever worked...i was just testing out tsgo out of curiosity. i thought maybe i'd tried a couple weeks ago and it worked but could be wrong)

[ahejlsberg]

This looks to be a bug in the declaration file emitter, specifically the inability to handle ast.KindCommonJSExport nodes.

[jakebailey]

Yeah, and we actually even skip all tests with allowJs set for emit (which includes declaration emit). That being said, this particular crash is not actually in our test suite (even when I reenable it, which is only possible after #1189 + #1195).

[cmdcolin]

thanks for looking into this. We do a number of fairly odd things in that monorepo so if there is something out of scope, feel free to ignore, but I mainly reported it as I thought null pointer bugs would be of interest!