Fix nil pointer dereference in code actions when diagnostic code is nil

[Copilot]

The language server panics when processing code action requests containing diagnostics with nil Code fields. The LSP protocol allows Diagnostic.Code to be omitted, but the handler attempted to dereference it without a nil check.

Changes

• internal/ls/codeactions.go: Add nil check for diag.Code before accessing diag.Code.Integer

Example

// Before: panics when diag.Code is nil
if diag.Code.Integer == nil {
    continue
}

// After: safely handles nil Code
if diag.Code == nil || diag.Code.Integer == nil {
    continue
}

[!WARNING]

Original prompt

---

This section details on the original issue you should resolve

<filter_complete></filter_complete>

<issue_title>codeactions - panic</issue_title>
<issue_description>## Stack trace

[11:17:53.127] Updated watches in 0s
panic handling request textDocument/codeAction runtime error: invalid memory address or nil pointer dereference goroutine 557015 [running]:
runtime/debug.Stack()
	runtime/debug/stack.go:26 +0x5e
github.com/microsoft/typescript-go/internal/lsp.(*Server).recover(0xc0000ecdc0, 0xc183e63260)
	github.com/microsoft/typescript-go/internal/lsp/server.go:572 +0x58
panic({0x7ff658ba41e0?, 0x7ff6595197a0?})
	runtime/panic.go:783 +0x132
github.com/microsoft/typescript-go/internal/ls.(*LanguageService).ProvideCodeActions(0xc183b9a180, {0x7ff658f0d860, 0xc183b748c0}, 0xc114034cc0)
	github.com/microsoft/typescript-go/internal/ls/codeactions.go:67 +0x18d
github.com/microsoft/typescript-go/internal/lsp.(*Server).handleCodeAction(0xc0002a0b40?, {0x7ff658f0d860?, 0xc183b748c0?}, 0xc0c8c1c900?, 0x82?)
	github.com/microsoft/typescript-go/internal/lsp/server.go:931 +0x25
github.com/microsoft/typescript-go/internal/lsp.init.func1.registerLanguageServiceDocumentRequestHandler[...].28({0x7ff658f0d860, 0xc183b748c0}, 0xc183e63260)
	github.com/microsoft/typescript-go/internal/lsp/server.go:558 +0x11a
github.com/microsoft/typescript-go/internal/lsp.(*Server).handleRequestOrNotification(0xc0000ecdc0, {0x7ff658f0d860, 0xc183b748c0}, 0xc183e63260)
	github.com/microsoft/typescript-go/internal/lsp/server.go:451 +0x10d
github.com/microsoft/typescript-go/internal/lsp.(*Server).dispatchLoop.func1()
	github.com/microsoft/typescript-go/internal/lsp/server.go:356 +0x3a
created by github.com/microsoft/typescript-go/internal/lsp.(*Server).dispatchLoop in goroutine 10
	github.com/microsoft/typescript-go/internal/lsp/server.go:376 +0x9ad

[Error - 11:17:54 AM] Request textDocument/codeAction failed.
  Message: InternalError: panic handling request textDocument/codeAction: runtime error: invalid memory address or nil pointer dereference
  Code: -32603 

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes codeactions - panic #2075

Original prompt

---

This section details on the original issue you should resolve

<issue_title>codeactions - panic</issue_title>
<issue_description>## Stack trace

[11:17:53.127] Updated watches in 0s
panic handling request textDocument/codeAction runtime error: invalid memory address or nil pointer dereference goroutine 557015 [running]:
runtime/debug.Stack()
	runtime/debug/stack.go:26 +0x5e
github.com/microsoft/typescript-go/internal/lsp.(*Server).recover(0xc0000ecdc0, 0xc183e63260)
	github.com/microsoft/typescript-go/internal/lsp/server.go:572 +0x58
panic({0x7ff658ba41e0?, 0x7ff6595197a0?})
	runtime/panic.go:783 +0x132
github.com/microsoft/typescript-go/internal/ls.(*LanguageService).ProvideCodeActions(0xc183b9a180, {0x7ff658f0d860, 0xc183b748c0}, 0xc114034cc0)
	github.com/microsoft/typescript-go/internal/ls/codeactions.go:67 +0x18d
github.com/microsoft/typescript-go/internal/lsp.(*Server).handleCodeAction(0xc0002a0b40?, {0x7ff658f0d860?, 0xc183b748c0?}, 0xc0c8c1c900?, 0x82?)
	github.com/microsoft/typescript-go/internal/lsp/server.go:931 +0x25
github.com/microsoft/typescript-go/internal/lsp.init.func1.registerLanguageServiceDocumentRequestHandler[...].28({0x7ff658f0d860, 0xc183b748c0}, 0xc183e63260)
	github.com/microsoft/typescript-go/internal/lsp/server.go:558 +0x11a
github.com/microsoft/typescript-go/internal/lsp.(*Server).handleRequestOrNotification(0xc0000ecdc0, {0x7ff658f0d860, 0xc183b748c0}, 0xc183e63260)
	github.com/microsoft/typescript-go/internal/lsp/server.go:451 +0x10d
github.com/microsoft/typescript-go/internal/lsp.(*Server).dispatchLoop.func1()
	github.com/microsoft/typescript-go/internal/lsp/server.go:356 +0x3a
created by github.com/microsoft/typescript-go/internal/lsp.(*Server).dispatchLoop in goroutine 10
	github.com/microsoft/typescript-go/internal/lsp/server.go:376 +0x9ad

[Error - 11:17:54 AM] Request textDocument/codeAction failed.
  Message: InternalError: panic handling request textDocument/codeAction: runtime error: invalid memory address or nil pointer dereference
  Code: -32603 

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes codeactions - panic #2075

---

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[Copilot]

Pull Request Overview

This PR fixes a nil pointer dereference panic in the code actions handler that occurs when a diagnostic has a nil Code field. The panic was happening when the code attempted to access diag.Code.Integer without first checking if diag.Code itself was nil.

Key changes:

• Added nil check for diag.Code before accessing diag.Code.Integer in the diagnostic processing loop