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

internal/ls/codeactions.go

@@ -64,7 +64,7 @@ func (l *LanguageService) ProvideCodeActions(ctx context.Context, params *lsprot
 	// Process diagnostics in the context to generate quick fixes
 	if params.Context != nil && params.Context.Diagnostics != nil {
 		for _, diag := range params.Context.Diagnostics {
-			if diag.Code.Integer == nil {
+			if diag.Code == nil || diag.Code.Integer == nil {
 				continue
 			}
 

internal/ls/codeactions_test.go

@@ -0,0 +1,91 @@
+package ls
+
+import (
+	"testing"
+
+	"github.com/microsoft/typescript-go/internal/lsp/lsproto"
+)
+
+// Test for issue: panic handling request textDocument/codeAction
+// This verifies that we safely handle nil diagnostic codes without panicking
+func TestCodeActionDiagnosticNilChecks(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		name       string
+		diagnostic *lsproto.Diagnostic
+		shouldSkip bool
+	}{
+		{
+			name: "nil Code field",
+			diagnostic: &lsproto.Diagnostic{
+				Range: lsproto.Range{
+					Start: lsproto.Position{Line: 0, Character: 0},
+					End:   lsproto.Position{Line: 0, Character: 10},
+				},
+				Message: "Test diagnostic with nil code",
+				Code:    nil,
+			},
+			shouldSkip: true,
+		},
+		{
+			name: "nil Integer in Code (string code instead)",
+			diagnostic: &lsproto.Diagnostic{
+				Range: lsproto.Range{
+					Start: lsproto.Position{Line: 0, Character: 0},
+					End:   lsproto.Position{Line: 0, Character: 10},
+				},
+				Message: "Test diagnostic with string code",
+				Code: &lsproto.IntegerOrString{
+					String:  stringPtr("TS1234"),
+					Integer: nil,
+				},
+			},
+			shouldSkip: true,
+		},
+		{
+			name: "valid Integer code",
+			diagnostic: &lsproto.Diagnostic{
+				Range: lsproto.Range{
+					Start: lsproto.Position{Line: 0, Character: 0},
+					End:   lsproto.Position{Line: 0, Character: 10},
+				},
+				Message: "Test diagnostic with integer code",
+				Code: &lsproto.IntegerOrString{
+					Integer: int32Ptr(2304),
+				},
+			},
+			shouldSkip: false,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			// Test the nil check logic that prevents the panic
+			// This mimics the check in ProvideCodeActions at line 67
+			shouldSkip := tc.diagnostic.Code == nil || tc.diagnostic.Code.Integer == nil
+
+			if shouldSkip != tc.shouldSkip {
+				t.Errorf("Expected shouldSkip=%v, got %v", tc.shouldSkip, shouldSkip)
+			}
+
+			// Verify we can safely access Code.Integer when shouldSkip is false
+			if !shouldSkip {
+				// This should not panic
+				errorCode := *tc.diagnostic.Code.Integer
+				if errorCode != 2304 {
+					t.Errorf("Expected error code 2304, got %d", errorCode)
+				}
+			}
+		})
+	}
+}
+
+func stringPtr(s string) *string {
+	return &s
+}
+
+func int32Ptr(i int32) *int32 {
+	return &i
+}