Fix nil pointer dereference and accept baselines

- Add nil check for node.Name() in checkWeakMapSetCollision
- Accept baseline for privateNameWeakMapCollision test

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

Author: Copilot

internal/checker/checker.go

@@ -10241,7 +10241,8 @@ func (c *Checker) recordPotentialCollisionWithWeakMapSetInGeneratedCode(node *as
 func (c *Checker) checkWeakMapSetCollision(node *ast.Node) {
 	enclosingBlockScope := ast.GetEnclosingBlockScopeContainer(node)
 	if c.nodeLinks.Get(enclosingBlockScope).flags&NodeCheckFlagsContainsClassWithPrivateIdentifiers != 0 {
-		if name := node.Name(); ast.IsIdentifier(name) {
+		name := node.Name()
+		if name != nil && ast.IsIdentifier(name) {
 			c.errorSkippedOnNoEmit(node, diagnostics.Compiler_reserves_name_0_when_emitting_private_identifier_downlevel, name.Text())
 		}
 	}

testdata/baselines/reference/submodule/compiler/privateNameWeakMapCollision.errors.txt

@@ -0,0 +1,17 @@
+privateNameWeakMapCollision.ts(2,9): error TS18027: Compiler reserves name 'WeakMap' when emitting private identifier downlevel.
+privateNameWeakMapCollision.ts(3,9): error TS18027: Compiler reserves name 'WeakSet' when emitting private identifier downlevel.
+
+
+==== privateNameWeakMapCollision.ts (2 errors) ====
+    function test() {
+        let WeakMap;
+            ~~~~~~~
+!!! error TS18027: Compiler reserves name 'WeakMap' when emitting private identifier downlevel.
+        let WeakSet;
+            ~~~~~~~
+!!! error TS18027: Compiler reserves name 'WeakSet' when emitting private identifier downlevel.
+        class C {
+            #x;
+        }
+    }
+