Initialisation

Added the packages and files for the backend server

node_modules/graphql/validation/rules/LoneSchemaDefinitionRule.mjs

@@ -0,0 +1,57 @@
+import { GraphQLError } from '../../error/GraphQLError.mjs';
+
+/**
+ * Lone Schema definition
+ *
+ * A GraphQL document is only valid if it contains only one schema definition.
+ */
+export function LoneSchemaDefinitionRule(context) {
+  var _ref, _ref2, _oldSchema$astNode;
+
+  const oldSchema = context.getSchema();
+  const alreadyDefined =
+    (_ref =
+      (_ref2 =
+        (_oldSchema$astNode =
+          oldSchema === null || oldSchema === void 0
+            ? void 0
+            : oldSchema.astNode) !== null && _oldSchema$astNode !== void 0
+          ? _oldSchema$astNode
+          : oldSchema === null || oldSchema === void 0
+          ? void 0
+          : oldSchema.getQueryType()) !== null && _ref2 !== void 0
+        ? _ref2
+        : oldSchema === null || oldSchema === void 0
+        ? void 0
+        : oldSchema.getMutationType()) !== null && _ref !== void 0
+      ? _ref
+      : oldSchema === null || oldSchema === void 0
+      ? void 0
+      : oldSchema.getSubscriptionType();
+  let schemaDefinitionsCount = 0;
+  return {
+    SchemaDefinition(node) {
+      if (alreadyDefined) {
+        context.reportError(
+          new GraphQLError(
+            'Cannot define a new schema within a schema extension.',
+            {
+              nodes: node,
+            },
+          ),
+        );
+        return;
+      }
+
+      if (schemaDefinitionsCount > 0) {
+        context.reportError(
+          new GraphQLError('Must provide only one schema definition.', {
+            nodes: node,
+          }),
+        );
+      }
+
+      ++schemaDefinitionsCount;
+    },
+  };
+}