First commit.

Signed-off-by: Chen Xiao <abigwc@gmail.com>

client/node_modules/langium/lib/utils/errors.js

@@ -0,0 +1,19 @@
+/******************************************************************************
+ * Copyright 2021 TypeFox GmbH
+ * This program and the accompanying materials are made available under the
+ * terms of the MIT License, which is available in the project root.
+ ******************************************************************************/
+export class ErrorWithLocation extends Error {
+    constructor(node, message) {
+        super(node ? `${message} at ${node.range.start.line}:${node.range.start.character}` : message);
+    }
+}
+export function assertUnreachable(_, message = 'Error: Got unexpected value.') {
+    throw new Error(message);
+}
+export function assertCondition(condition, message = 'Error: Condition is violated.') {
+    if (!condition) {
+        throw new Error(message);
+    }
+}
+//# sourceMappingURL=errors.js.map