DrmStatus type checks

Bug: 260065906
Change-Id: I1f290b744da748899d09821dc20e91f65430ef37
Test: MediaDrmClearKeyTest
diff --git a/drm/libmediadrm/DrmStatus.cpp b/drm/libmediadrm/DrmStatus.cpp
index 0258801..f622160 100644
--- a/drm/libmediadrm/DrmStatus.cpp
+++ b/drm/libmediadrm/DrmStatus.cpp
@@ -27,21 +27,20 @@
         return;
     }
 
-    std::string errMsg;
     auto val = errorDetails["cdmError"];
-    if (!val.isNull()) {
+    if (val.isInt()) {
         mCdmErr = val.asInt();
     }
     val = errorDetails["oemError"];
-    if (!val.isNull()) {
+    if (val.isInt()) {
         mOemErr = val.asInt();
     }
     val = errorDetails["context"];
-    if (!val.isNull()) {
+    if (val.isInt()) {
         mCtx = val.asInt();
     }
     val = errorDetails["errorMessage"];
-    if (!val.isNull()) {
+    if (val.isString()) {
         mErrMsg = val.asString();
     } else {
         mErrMsg = msg;