Division by zero errors

Sorry if this has already been spotted but I tried the latest dev copy and the bug is still in there.

When creating a new account, if the user submits the form without completing mandatory fields, such as user name, the following errors are produced.

warning: Invalid argument supplied for foreach() in ...bayesian.module on line 62. 
warning: asort() expects parameter 1 to be array, null given in ...bayesian.module on line 73. 
warning: array_keys() [function.array-keys]: The first argument should be an array in ...bayesian.module on line 78. 
warning: array_pop() [function.array-pop]: The argument should be an array in ...bayesian.module on line 82. 
warning: Division by zero in ...bayesian.module on line 97. 

As a temporary measure I've unchecked "Bayesian filter" in admin/settings/spam/filters. Interestingly I already had "Users" unchecked under "Content to filter" on admin/settings/spam.

Thanks :)