[SVLS-3853] handle the null case first before handling max depth (#465)

* handle the null case first before max depth

Author: joeyzhao2018

src/utils/tag-object.spec.ts

@@ -71,6 +71,8 @@ describe("tagObject", () => {
           level2_list: [null, true, "nice", { l3: "v3" }],
           level2_bool: true,
           level2_int: 2,
+          level2_null: null,
+          level2_empty_obj: {},
         },
         vals: [{ thingOne: 1 }, { thingTwo: 2 }],
       },
@@ -83,6 +85,8 @@ describe("tagObject", () => {
       ["function.request.level1.level2_list", '[null,true,"nice",{"l3":"v3"}]'],
       ["function.request.level1.level2_bool", "true"],
       ["function.request.level1.level2_int", "2"],
+      ["function.request.level1.level2_null", null],
+      ["function.request.level1.level2_empty_obj", "{}"],
       ["function.request.vals.0", '{"thingOne":1}'],
       ["function.request.vals.1", '{"thingTwo":2}'],
     ]);

src/utils/tag-object.ts

@@ -1,12 +1,12 @@
 const redactableKeys = ["authorization", "x-authorization", "password", "token"];
 
 export function tagObject(currentSpan: any, key: string, obj: any, depth = 0, maxDepth = 10): any {
-  if (depth >= maxDepth) {
-    return currentSpan.setTag(key, redactVal(key, JSON.stringify(obj).substring(0, 5000)));
-  }
   if (obj === null) {
     return currentSpan.setTag(key, obj);
   }
+  if (depth >= maxDepth) {
+    return currentSpan.setTag(key, redactVal(key, JSON.stringify(obj).substring(0, 5000)));
+  }
   depth += 1;
   if (typeof obj === "string") {
     let parsed: string;