UI: fix right click crash in debugger

Author: chrisws

src/ui/textedit.cpp

@@ -1259,7 +1259,7 @@ const char *TextEditInput::getNodeId() {
 
 char *TextEditInput::getWordBeforeCursor() {
   char *result;
-  if (_state.select_start == _state.select_end) {
+  if (_state.select_start == _state.select_end && _buf._len > 0) {
     int start, end;
     result = getSelection(&start, &end);
   } else {