Fix crash when completing at beginning of property name preceded by JSDoc

Fixed two issues:
1. Variable shadowing bug in getRelevantTokens where contextToken was declared with := instead of assigned with =, causing it to remain nil
2. Added nil checks in tryGetClassLikeCompletionSymbols to handle cases where contextToken is nil

These changes prevent the nil pointer dereference crash reported in the issue.

Co-authored-by: DanielRosenwasser <[email protected]>

Author: Copilot

internal/fourslash/tests/completionJSDocBeforeProperty_test.go

@@ -1444,7 +1444,7 @@ func (l *LanguageService) getCompletionData(
 		completionKind = CompletionKindMemberLike
 		// Declaring new property/method/accessor
 		isNewIdentifierLocation = true
-		if contextToken.Kind == ast.KindAsteriskToken {
+		if contextToken != nil && contextToken.Kind == ast.KindAsteriskToken {
 			keywordFilters = KeywordCompletionFiltersNone
 		} else if ast.IsClassLike(decl) {
 			keywordFilters = KeywordCompletionFiltersClassElementKeywords
@@ -1458,17 +1458,17 @@ func (l *LanguageService) getCompletionData(
 		}
 
 		var classElement *ast.Node
-		if contextToken.Kind == ast.KindSemicolonToken {
+		if contextToken != nil && contextToken.Kind == ast.KindSemicolonToken {
 			classElement = contextToken.Parent.Parent
-		} else {
+		} else if contextToken != nil {
 			classElement = contextToken.Parent
 		}
 		var classElementModifierFlags ast.ModifierFlags
 		if ast.IsClassElement(classElement) {
 			classElementModifierFlags = classElement.ModifierFlags()
 		}
 		// If this is context token is not something we are editing now, consider if this would lead to be modifier.
-		if contextToken.Kind == ast.KindIdentifier && !isCurrentlyEditingNode(contextToken, file, position) {
+		if contextToken != nil && contextToken.Kind == ast.KindIdentifier && !isCurrentlyEditingNode(contextToken, file, position) {
 			switch contextToken.Text() {
 			case "private":
 				classElementModifierFlags |= ast.ModifierFlagsPrivate
@@ -2750,7 +2750,7 @@ func getSourceFromOrigin(origin *symbolOriginInfo) string {
 func getRelevantTokens(position int, file *ast.SourceFile) (contextToken *ast.Node, previousToken *ast.Node) {
 	previousToken = astnav.FindPrecedingToken(file, position)
 	if previousToken != nil && position <= previousToken.End() && (ast.IsMemberName(previousToken) || ast.IsKeywordKind(previousToken.Kind)) {
-		contextToken := astnav.FindPrecedingToken(file, previousToken.Pos())
+		contextToken = astnav.FindPrecedingToken(file, previousToken.Pos())
 		return contextToken, previousToken
 	}
 	return previousToken, previousToken