Velocity errors in templates/jira/issue/field/priority-edit.vm

From my logs:

2005-06-23 08:15:46,608 ERROR [velocity] Left side ( '' ) of addition operation has null value. Operation not possible. templates/jira/issue/field/priority-edit.vm [line 12, column 60]
2005-06-23 08:15:46,608 ERROR [velocity] RHS of #set statement is null. Context will not be modified. templates/jira/issue/field/priority-edit.vm [line 12, column 1]
2005-06-23 08:15:46,640 ERROR [velocity] Left side of addition operation is not a valid type. Currently only integers (1,2,3...) and Integer type is supported. templates/jira/issue/field/priority-edit.vm [line 12, column 55]

Probably this hides some functionality on the EditIssue page, and it is also flooding my logs with error messages.