in lib/eventstream_rpc_utils.ts [373:382]
export function validateValueAsBlob(value : any, propertyName?: string, type?: string) {
if (value === undefined) {
throwMissingPropertyError(propertyName, type);
}
/* there doesn't seem to be a good way of checking if something is an ArrayBuffer */
if ((typeof value !== 'string') && !ArrayBuffer.isView(value) && (!value.byteLength || !value.maxByteLength)) {
throwInvalidPropertyValueError('a value convertible to a binary payload', propertyName, type);
}
}