Function validateNodeExists

packages/core/src/hydration/error_handling.ts:143–166

(
  node: RNode | null,
  lView: LView | null = null,
  tNode: TNode | null = null,
)

 * Validates that a node exists or throws
 */
export function validateNodeExists(
  node: RNode | null,
  lView: LView | null = null,
  tNode: TNode | null = null,
): void {
  if (!node) {
    const header =
      'During hydration, Angular expected an element to be present at this location.\n\n';
    let expected = '';
    let footer = '';
    if (lView !== null && tNode !== null) {
      expected = describeExpectedDom(lView, tNode, false);
      footer = getHydrationErrorFooter();

      // Since the node is missing, we use the closest node to attach the error to
      markRNodeAsHavingHydrationMismatch(unwrapRNode(lView[HOST]!), expected, '');
    }

    throw new RuntimeError(
      RuntimeErrorCode.HYDRATION_MISSING_NODE,
      `${header}${expected}\n\n${footer}`,
    );
  }
}

/**
 * Builds the hydration error message when a node is not found