···435435436436 // assume enums do not contain transformable values
437437 if (schema.type !== 'enum') {
438438- if (!schema.items.every((item) => item.type === 'number')) {
438438+ if (
439439+ !(schema.items ?? []).every((item) =>
440440+ (
441441+ ['boolean', 'integer', 'null', 'number', 'string'] as ReadonlyArray<
442442+ typeof item.type
443443+ >
444444+ ).includes(item.type),
445445+ )
446446+ ) {
439447 console.warn(
440448 `❗️ Transformers warning: schema ${JSON.stringify(schema)} is too complex and won't be currently processed. This will likely produce an incomplete transformer which is not what you want. Please open an issue if you'd like this improved https://github.com/hey-api/openapi-ts/issues`,
441449 );