Fix parent node walk termination condition in getConstrainedTypeVariable

Author: ahejlsberg

src/compiler/checker.ts

@@ -7395,7 +7395,7 @@ namespace ts {
 
         function getConstrainedTypeVariable(typeVariable: TypeVariable, node: Node) {
             let constraints: Type[];
-            while (isPartOfTypeNode(node)) {
+            while (node && !isStatement(node)) {
                 const parent = node.parent;
                 if (parent.kind === SyntaxKind.ConditionalType && node === (<ConditionalTypeNode>parent).trueType) {
                     const constraint = getImpliedConstraint(typeVariable, (<ConditionalTypeNode>parent).checkType, (<ConditionalTypeNode>parent).extendsType);