add temporary exception

plugin/banana.vim

@@ -26,7 +26,10 @@ fun! s:Enc()
 	python3 << EOL
 from banana import text2banana,get_selected_text,replace_selected_text
 
-replace_selected_text(text2banana(get_selected_text()))
+try:
+    replace_selected_text(text2banana(get_selected_text()))
+except:
+    print("banana: select the text you want to convert")
 
 EOL
 endfun!
@@ -41,4 +44,4 @@ EOL
 endfun!
 
 let &cpo= s:keepcpo
-unlet s:keepcpo
+unlet s:keepcpo