Description : In the simulator, if you insert without inputting anything in the text-area, then inserts 0 into search tree.
Steps to reproduce : Open simulator under Search Tree experiment. Without typing anything in text-area, click on insert button.
Expected result : Error message to input a number.
Actual result : 0 is getting inserted.
Screenshot :
Description : In the simulator, if you insert without inputting anything in the text-area, then inserts 0 into search tree. Steps to reproduce : Open simulator under Search Tree experiment. Without typing anything in text-area, click on insert button. Expected result : Error message to input a number. Actual result : 0 is getting inserted. Screenshot :![Screenshot (22)](https://user-images.githubusercontent.com/42439398/54489589-beeccc80-48d3-11e9-987c-d2b4bb83b0d4.png)