It’s hard to say, without seeing a sample of your code, but I’ve got some guesses that might help you narrow things down a little.
That said, it’s highly likely line 107 is trying to perform a math operation on a variable whose value isn’t numeric. Specifically, if you
*create a variable with the value of
"blah blah", then accidentally try to add to, subtract from, multiply, or divide it, you’ll get an error that says
Error: line [whatever]: Not a number: blah blah
For example, the following code duplicates the error you’re reporting:
*create variable1 "blah blah"
*set variable1 +20
If the variable were created with a different value, you’d get a different error report. For example, the following:
*create variable1 "tall hats"
*set variable1 +5
That will report an error reading
line [whatever]: Not a number: tall hats