diff --git a/src/base/extStore.js b/src/base/extStore.js
index 63deaea..e598728 100644
--- a/src/base/extStore.js
+++ b/src/base/extStore.js
@@ -68,17 +68,21 @@ function clearFunctionDeclarationText(func) {
  * @returns {string}
  */
 function getScriptTagInjectionText(func, registrationName) {
-    let funcHasName = func.name && func.name.trim() !== '';
-    if (func.startWith('function')) {
-        let label = `function ${registrationName}`;
-        let isNameInFuncText = func.startWith(label);
-        if (funcHasName && isNameInFuncText) {
+    let funcHasName;
+    if (typeof func === 'function') {
+        funcHasName = ((func.name) && func.name.trim() !== '');
+    }
+
+    if (func.startsWith('function')) {
+        let label = ` function ${registrationName}`;
+        let isNameInFuncText = func.startsWith(label);
+        if (isNameInFuncText) {
             return func;
         } else {
-            return [label, '(', func.split('(', 1)[1]].join('')
+            return [label, '(', func.split('(').slice(1).join('(')].join('')
         }
     } else {
-        return `const ${registrationName} = ${func}; `;
+        return ` const ${registrationName} = ${func}; `;
     }
 }