Fast Formula Empty String Not Allowed Using Replace

Summary

Not able to remove characters using Replace function in a fast formula

Content

I am getting a fast formula compile error that makes no sense.  In the code below, using the Replace function,  I am simply trying to remove any spaces from the results of the line before it.  I get an  "Empty String Not Allowed" compile error for that line.  I tried using TRANSLATE and that gave me the same error.  Does anyone have any ideas why this is happening?  It seems like a bug.

 l_meaning = 'X'
 l_meaning = TRIM(PER_PERSON_EIT_ALL_PEI_INFORMATION1[i])