fix(core): add unknown[] when items is not defined (#1757)

packages/core/src/getters/array.ts

@@ -3,6 +3,7 @@ import { SchemaObject as SchemaObject31 } from 'openapi3-ts/oas31';
 import { ContextSpecs, ScalarValue } from '../types';
 import { resolveObject } from '../resolvers/object';
 import { resolveExampleRefs } from '../resolvers';
+import { compareVersions } from '../utils';
 
 /**
  * Return the output type from an array
@@ -80,6 +81,18 @@ export const getArray = ({
       example: schema.example,
       examples: resolveExampleRefs(schema.examples, context),
     };
+  } else if (
+    compareVersions(context.specs[context.specKey].openapi, '3.1', '>=')
+  ) {
+    return {
+      value: 'unknown[]',
+      imports: [],
+      schemas: [],
+      isEnum: false,
+      type: 'array',
+      isRef: false,
+      hasReadonlyProps: false,
+    };
   } else {
     throw new Error(
       `All arrays must have an \`items\` key defined (name=${name}, schema=${JSON.stringify(schema)})`,