Merge pull request #267 from tbannister/backspace-fix

Fix backspace on empty input issue.

Author: AydinHassan

src/Input/InputIO.php

@@ -77,6 +77,9 @@ public function collect(Input $input) : InputResult
                     case InputCharacter::BACKSPACE:
                         if (!empty($inputValue)) {
                             $inputValue = substr($inputValue, 0, -1);
+                            if (!is_string($inputValue)) {
+                                $inputValue = '';
+                            }
                             $this->parentMenu->redraw();
                             $this->drawInput($input, $inputValue);
                         }