Ruby json2csv fails - ruby

Question

using
C:\RubyLearnToProgram>json2csv convert sample.json
results in following error:
Converting sample.json error: undefined method `keys' for
"PREPARED":String
The sample.json:
{
"preparationState": "PREPARED",
"consumerUsageStorageInstruction": {
"de": "gebruik",
"fr": "gebruik",
"en": "gebruik"
},
"npc": "1234",
"drainedWeight": "320.0GR",
"isBaseUnit": "true",
"packagingMarkedExpirationDateType": "BEST_BEFORE_DATE",
"numberOfServingsPerPackage": "100",
"functionalName": "Babbelaars",
"preparationInstructions": {
"de": "koken",
"fr": "koken",
"en": "koken"
},
"brandName": "Test lets try this one",
"manufacturerGln": "5060263871002",
"packagingRefuseObligationName": "ARA",
"gln": "5060263871002",
"height": "129.0MM",
"percentageOfAlcoholByVolume": "0.0",
"dailyValueIntakeReference": "10 a day keeps the doctor away",
"allergenStatement": {
"de": "Enthalt: Milch (Laktose)",
"fr": "Contient: lait de vache (lactose)",
"en": "Bevat: koemelk (lactose)"
},
"isPackagingMarkedReturnable": "false",
"netContent": "325.0GR",
"regulatedProductName": "Babbelaars",
"itemThumbnail": "/a/16257a91e7c42b64fdc7ad91292dce85/babbelaars.png",
"packages": [
{
"height": "100.0CM",
"containedGtin": "90000000000003",
"gtin": "91000000000002",
"width": "50.0CM",
"netContent": "100.0EA",
"packageUnitIndicator": "CASE",
"depth": "60.0CM",
"containedAmount": "10",
"grossWeight": "109.0KG"
}
],
"isVariableUnit": "false",
"taxRate": "STANDARD",
"width": "67.0MM",
"targetMarket": "528",
"gpc": "10000005",
"nameOfInformationProvider": "LANSA",
"depth": "67.0MM",
"grossWeight": "350.0GR",
"nutrients": [{
"percentageOfDailyValueIntake":"0.1","measurementPrecision":"APPROXIMATELY","quantityContainedServingSize":"1.0","quantityContainedHouseHoldServingSize":"10.0","quantityContainedUnit":"GR","nutrientTypeCode":"CHOAVL-"
},{
"percentageOfDailyValueIntake":"0.2","measurementPrecision":"APPROXIMATELY","quantityContainedServingSize":"2.0","quantityContainedHouseHoldServingSize":"20.0","quantityContainedUnit":"E14","nutrientTypeCode":"ENER-"
},{
"percentageOfDailyValueIntake":"0.3","measurementPrecision":"APPROXIMATELY","quantityContainedServingSize":"3.0","quantityContainedHouseHoldServingSize":"30.0","quantityContainedUnit":"GR","nutrientTypeCode":"FASAT"
},{
"percentageOfDailyValueIntake":"0.4","measurementPrecision":"APPROXIMATELY","quantityContainedServingSize":"4.0","quantityContainedHouseHoldServingSize":"40.0","quantityContainedUnit":"KJO","nutrientTypeCode":"ENER-"
},{
"percentageOfDailyValueIntake":"0.5","measurementPrecision":"APPROXIMATELY","quantityContainedServingSize":"5.0","quantityContainedHouseHoldServingSize":"50.0","quantityContainedUnit":"GR","nutrientTypeCode":"FIBTG"
},{
"percentageOfDailyValueIntake":"0.6","measurementPrecision":"APPROXIMATELY","quantityContainedServingSize":"6.0","quantityContainedHouseHoldServingSize":"60.0","quantityContainedUnit":"GR","nutrientTypeCode":"PRO-"
},{
"percentageOfDailyValueIntake":"0.7","measurementPrecision":"APPROXIMATELY","quantityContainedServingSize":"7.0","quantityContainedHouseHoldServingSize":"70.0","quantityContainedUnit":"GR","nutrientTypeCode":"FAT"
},{
"percentageOfDailyValueIntake":"0.8","measurementPrecision":"APPROXIMATELY","quantityContainedServingSize":"8.0","quantityContainedHouseHoldServingSize":"80.0","quantityContainedUnit":"GR","nutrientTypeCode":"SUGAR-"
},{
"percentageOfDailyValueIntake":"0.9","measurementPrecision":"APPROXIMATELY","quantityContainedServingSize":"9.0","quantityContainedHouseHoldServingSize":"90.0","quantityContainedUnit":"GR","nutrientTypeCode":"SALTEQ"
}],
"ingredientStatement": {
"de": "Zucker, Glukosesirup, Zuckersirup, Butter (3%), Salz.",
"fr": "sucre, sirop de glucose, sirop de sucre, beurre (3%), sel.",
"en": "sugar, glucose syrup, sugar syrup, butter (3%), salt."
},
"isItemReturnable": "false",
"shortDescription": {
"en": "Babbelaars"
},
"allergens": [
{
"allergenTypeCode": "BB",
"levelOfContainment": "CONTAINS"
}
],
"contactName": "LANSAEU1169",
"startAvailabilityDate": "2015-05-19",
"myattribute": "MyPostedEach",
"minimumLifespanFromTimeOfArrival": "8",
"householdServingSize": "household serving size",
"isDispatchUnit": "false",
"isBasePriceDeclarationRelevant": "false",
"allergenSpecificationAgency": "EU",
"isOrderableUnit": "false",
"allergenSpecificationName": "1169/2011",
"additives": [
{
"additiveName": "additive sample name",
"levelOfContainment": "CONTAINS"
}
],
"minimumLifespanFromTimeOfProduction": "10",
"baseUnitIndicator": "BASE_UNIT_OR_EACH",
"effectiveDate": "2015-05-19",
"servingSize": "GR",
"countryOfOrigin": "528",
"preparationType": "PRESSURE_COOKING",
"supplierItemNumber": "324324234",
"gtin": "90000000000003",
"pallets": [
{
"palletTypeCode": "37",
"height": "10.0MR",
"optionalGtin": "92000000000001",
"containedGtin": "91000000000002",
"palletTermsAndConditions": "3",
"width": "250.0CM",
"quantityOfLayersPerPallet": "5",
"palletUnitIndicator": "PALLET",
"depth": "120.0CM",
"containedAmount": "50",
"grossWeight": "1200.0KG",
"logisticsUnitStackingFactor": "10"
}
],
"barCodeType": "EAN_UCC_13_SYMBOL",
"nameOfManufacturer": "LANSA",
"compulsoryAdditivesLabelInformation": {
"de": "comp add label",
"fr": "comp add label",
"en": "comp add label"
},
"isInvoiceUnit": "false",
"isConsumerUnit": "true",
"packagingTypeCode": "CAN",
"communicationAddress": "Leliehof 26, 4841 ML PRINSENBEEK",
"itemImage": "/a/d59455129b92fb21dd00a97746a81439/babbelaars.png",
"isPackagingExemptFromRefuseObligation": "NOT_APPLICABLE"
}
Could you help me with this, I'm trying to get all keys and nested keys to create a dynamic conversion of values. Thanks in advance, Greetings Danny