make isExpressionNode an asserts function

Author: Andarist

src/compiler/checker.ts

@@ -24118,7 +24118,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 const templateType = (getApparentTypeOfContextualType(sourceValueDeclaration.parent.parent as Expression, ContextFlags.NoConstraints) as MappedType).templateType;
                 if (templateType) {
                     Debug.assertNode(sourceValueDeclaration, isExpressionNode);
-                    pushContextualType(sourceValueDeclaration as any as Expression, templateType, /*isCache*/ false);
+                    pushContextualType(sourceValueDeclaration, templateType, /*isCache*/ false);
                     inferFromIntraExpressionSites([inference], intraExpressionInferenceSites);
                     popContextualType();
                 }