route validation and prevent navigation from breaking on re-cklick

templates/sell_sendError.html

@@ -1,5 +1,6 @@
-<h1>ERROR occured whilst sending form data. Please try again!</h1>
+<h1>ERROR occured whilst sending form data.</h1>
 
+Please check your internet connection and try to <a type="submit" class="btn btn-success"  onclick="ibuyproperties.sellForm.sendForm();">resubmit</a><br>
 <b>... or alternatively send the data via <button class="btn btn-success" onclick="generateMail();" id="mailLink">e-mail</button>.</b>
 
 <script>
@@ -8,4 +9,4 @@
     console.log("Fallback Mail Content",content);
     window.location.href=content;
   }
-</script>
+</script>