fix: string samples should also be json stringified. (#6412)

fixes #6120

src/core/utils.js

@@ -560,7 +560,9 @@ export const getSampleSchema = (schema, contentType="", config={}) => {
 
   const res = memoizedSampleFromSchema(schema, config)
 
-  return typeof res === "object" ? JSON.stringify(res, null, 2) : res
+  return typeof res === "object" || typeof res === "string" 
+    ? JSON.stringify(res, null, 2) 
+    : res
 }
 
 export const parseSearch = () => {

test/unit/core/utils.js

@@ -1494,7 +1494,7 @@ describe("utils", () => {
       Date = oriDate
     })
     
-    it("should not unnecessarily stringify non-object values", () => {
+    it("should stringify string values", () => {
       // Given
       const res = getSampleSchema({
         type: "string",
@@ -1502,7 +1502,17 @@ describe("utils", () => {
       })
       
       // Then
-      expect(res).toEqual(new Date().toISOString())
+      expect(res).toEqual(JSON.stringify(new Date().toISOString()))
+    })
+
+    it("should not unnecessarily stringify non-object values", () => {
+      // Given
+      const res = getSampleSchema({
+        type: "number"
+      })
+      
+      // Then
+      expect(res).toEqual(0)
     })
   })