Probably an infinite loop_type loop.
The index variable for a "while" loop created using the while do...end while statement or a "repeat" loop created using the repeat...until statement isn't modified inside the loop body. When the index variable isn't modified, no exit condition exists and an infinite loop occurs. Loop_type indicates the type of loop that might be infinite.
Be sure that an appropriate exit condition exists for the boolexp parameter specified for each of these statements. For the while do...end while statement, the boolexp must return false for the exit condition to occur. For the repeat...until statement, boolexp must return true for the exit condition to occur.