bug in functions.js: Cannot read property 'replace' of undefined

Signed-off-by: Marc Delisle <marc@infomarc.info>

ChangeLog

@@ -12,6 +12,7 @@ phpMyAdmin - ChangeLog
 - bug       server_privileges.js: cannot read property
 - bug #4527 Importing ODS files with column names having trailing spaces fails
 - bug #4413 Navigation Error in Nav Tree for Search Results Past the First Page
+- bug       functions.js: Cannot read property 'replace' of undefined
 
 4.2.7.1 (2014-08-17)
 - bug #4501 [security] XSS in table browse page

js/functions.js

@@ -3835,12 +3835,16 @@ function PMA_clearSelection() {
  * HTML escaping
  */
 function escapeHtml(unsafe) {
-    return unsafe
-        .replace(/&/g, "&")
-        .replace(/</g, "&lt;")
-        .replace(/>/g, "&gt;")
-        .replace(/"/g, "&quot;")
-        .replace(/'/g, "&#039;");
+    if (typeof(unsafe) != 'undefined') {
+        return unsafe
+            .replace(/&/g, "&amp;")
+            .replace(/</g, "&lt;")
+            .replace(/>/g, "&gt;")
+            .replace(/"/g, "&quot;")
+            .replace(/'/g, "&#039;");
+    } else {
+        return false;
+    }
 }
 
 /**