Steps to reproduce:

Consider the following case1:

1. I create a trapper item.
2. I set preprocessing with single multiplication step. Multiplier is set to {$MULTIPLIER}.
3. I didn't define a value for this macro.

Now I always get zeroes for a value as {$MULTIPLIER} resolves to empty string and empty string is considered to be 0.

Consider the following case2:

1. I create a trapper item.
2. I set preprocessing with single multiplication step. Multiplier is set to {$MULTIPLIER}.
3. I define a value for this macro as 10X.

Now I always get 10 for a value as {$MULTIPLIER} resolves to 10, although this is not a number.

Expected:
The Item should become unsupported with information about error reason