line 3138 in your main_vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv7 file
will tell you which line in your b4a source has triggered the exception.
the file is found in a subfolder of objects --> source ---> etc ---> etc --> main.java.
look in your project's folder.
the remedy would depend on whether or not user input is involved. someone
is responsible for allowing the empty string.
if you go to line 3138 in main.java, you will see something like this:
//BA.debugLineNum = 765;BA.debugLine="ToastMessageShow ...
that tells you to go to line 765 in your b4a source for the statement that
triggered the exception.