Correctly propagate frontend call warnings (fixes #211)

Change-Id: Ia571b8e6b0ba0a4edbf0501254ce2bc115f18cf6
diff --git a/dev/js/src/api.js b/dev/js/src/api.js
index 80391d8..3b3b821 100644
--- a/dev/js/src/api.js
+++ b/dev/js/src/api.js
@@ -169,10 +169,16 @@
             return;
           };
 
-          if (retJSObj !== undefined && retJSObj["errors"] !== undefined) {
-            retJSObj["errors"].forEach(
-              e => KorAP.log(e[0], e[1] || "Unknown")
-            );
+          if (retJSObj !== undefined) {
+            if (retJSObj["errors"] !== undefined) {
+              retJSObj["errors"].forEach(
+                e => KorAP.log(e[0], e[1] || "Unknown")
+              );
+            } else if (retJSObj["warnings"] !== undefined) {
+              retJSObj["warnings"].forEach(
+                e => KorAP.log(e[0], e[1] || "Unknown", null, 'warn')
+              );
+            }
           }
 
           else if (this.status !== 200) {