Empty string in type reference directive crashes

[andrewbranch]

Stack trace

panic: runtime error: index out of range [0] with length 0

goroutine 50 [running]:
github.com/microsoft/typescript-go/internal/module.MangleScopedPackageName({0x140000cfb90?, 0x1022c0980?})
	/Users/andrew/Developer/microsoft/typescript-go/internal/module/util.go:48 +0x110
github.com/microsoft/typescript-go/internal/module.(*resolutionState).mangleScopedPackageName(0x140002124e0, {0x140000cfb90, 0x0})
	/Users/andrew/Developer/microsoft/typescript-go/internal/module/resolver.go:385 +0x34
github.com/microsoft/typescript-go/internal/module.(*resolutionState).getCandidateFromTypeRoot(0x140002124e0, {0x14000216680, 0x3b})
	/Users/andrew/Developer/microsoft/typescript-go/internal/module/resolver.go:379 +0xc0
github.com/microsoft/typescript-go/internal/module.(*resolutionState).resolveTypeReferenceDirective(0x140002124e0, {0x14000236180?, 0x14000309140?, 0x2b?}, 0x0, 0x0)
	/Users/andrew/Developer/microsoft/typescript-go/internal/module/resolver.go:335 +0x49c
github.com/microsoft/typescript-go/internal/module.(*Resolver).ResolveTypeReferenceDirective(0x14000364780, {0x140000cfb90, 0x0}, {0x14000309140, 0x32}, 0x1, {0x102bbb788, 0x0})
	/Users/andrew/Developer/microsoft/typescript-go/internal/module/resolver.go:217 +0x2cc
github.com/microsoft/typescript-go/internal/compiler.(*fileLoader).resolveTypeReferenceDirectives(0x14000343508, 0x1400031f440)
	/Users/andrew/Developer/microsoft/typescript-go/internal/compiler/fileloader.go:463 +0x1bc
github.com/microsoft/typescript-go/internal/compiler.(*parseTask).load(0x1400031f440, 0x14000343508)
	/Users/andrew/Developer/microsoft/typescript-go/internal/compiler/filesparser.go:91 +0x2d8
github.com/microsoft/typescript-go/internal/compiler.(*filesParser).start.func1()
	/Users/andrew/Developer/microsoft/typescript-go/internal/compiler/filesparser.go:220 +0x170
github.com/microsoft/typescript-go/internal/core.(*parallelWorkGroup).Queue.func1()
	/Users/andrew/Developer/microsoft/typescript-go/internal/core/workgroup.go:42 +0x50
created by github.com/microsoft/typescript-go/internal/core.(*parallelWorkGroup).Queue in goroutine 49
	/Users/andrew/Developer/microsoft/typescript-go/internal/core/workgroup.go:40 +0x7c
[Error - 3:32:42 PM] The typescript.native-preview-lsp server crashed 5 times in the last 3 minutes. The server will not be restarted. See the output for more information.
[Error - 3:32:42 PM] Server process exited with code 2.
Restarting language server...
[15:32:48.894] Processed 1 file changes in 26.542µs
panic: runtime error: index out of range [0] with length 0

goroutine 7 [running]:
github.com/microsoft/typescript-go/internal/module.MangleScopedPackageName({0x140001c1b90?, 0x102bb0980?})
	/Users/andrew/Developer/microsoft/typescript-go/internal/module/util.go:48 +0x110
github.com/microsoft/typescript-go/internal/module.(*resolutionState).mangleScopedPackageName(0x1400020a410, {0x140001c1b90, 0x0})
	/Users/andrew/Developer/microsoft/typescript-go/internal/module/resolver.go:385 +0x34
github.com/microsoft/typescript-go/internal/module.(*resolutionState).getCandidateFromTypeRoot(0x1400020a410, {0x14000202680, 0x3b})
	/Users/andrew/Developer/microsoft/typescript-go/internal/module/resolver.go:379 +0xc0
github.com/microsoft/typescript-go/internal/module.(*resolutionState).resolveTypeReferenceDirective(0x1400020a410, {0x14000228180?, 0x14000029380?, 0x2b?}, 0x0, 0x0)
	/Users/andrew/Developer/microsoft/typescript-go/internal/module/resolver.go:335 +0x49c
github.com/microsoft/typescript-go/internal/module.(*Resolver).ResolveTypeReferenceDirective(0x1400007a840, {0x140001c1b90, 0x0}, {0x14000029380, 0x32}, 0x1, {0x1034ab788, 0x0})
	/Users/andrew/Developer/microsoft/typescript-go/internal/module/resolver.go:217 +0x2cc
github.com/microsoft/typescript-go/internal/compiler.(*fileLoader).resolveTypeReferenceDirectives(0x1400032b508, 0x14000311440)
	/Users/andrew/Developer/microsoft/typescript-go/internal/compiler/fileloader.go:463 +0x1bc
github.com/microsoft/typescript-go/internal/compiler.(*parseTask).load(0x14000311440, 0x1400032b508)
	/Users/andrew/Developer/microsoft/typescript-go/internal/compiler/filesparser.go:91 +0x2d8
github.com/microsoft/typescript-go/internal/compiler.(*filesParser).start.func1()
	/Users/andrew/Developer/microsoft/typescript-go/internal/compiler/filesparser.go:220 +0x170
github.com/microsoft/typescript-go/internal/core.(*parallelWorkGroup).Queue.func1()
	/Users/andrew/Developer/microsoft/typescript-go/internal/core/workgroup.go:42 +0x50
created by github.com/microsoft/typescript-go/internal/core.(*parallelWorkGroup).Queue in goroutine 6
	/Users/andrew/Developer/microsoft/typescript-go/internal/core/workgroup.go:40 +0x7c

[Twacqwq]

@andrewbranch Even though packageName is usually not empty, but we still check its length for empty to avoid panic. If possible, should I submit a PR to fix it? 🤔

[andrewbranch]

@Twacqwq go for it 👍