Function working with String but not with Column

[Anonymous]

I got this line

Additional_Info = Table.AddColumn(Location_Office, "Additional_Info", each getRemaining("test   test", Text.Split(Text.Combine({[Column2], [Column3], [Column4], [Column5]}, "#(lf)"), "#(lf)")))

which refers to these two functions: 

getRemaining = (text, list) => //Read from the column "Column1" and "Column2", "Column3", "Column4", "Column5"
    let 
        Combined = if text <> null then let
        list1 = Text.Split(text, "#(lf)"),
        temp = List.Difference(list1, list), //Look for matches; Fitlering them out
        Combined = removeMultipleSpaces(Text.Combine(temp, " "))
        in
        Combined
        else Combined= null
    in
        Combined, //Returns all NOT matching results

    removeMultipleSpaces = (text) =>
    let
        //Split the text at each space character
        SplitText = Text.Split(text," "),
        //Remove the blank items from the list
        ListNonBlankValues = List.Select(SplitText,each _<> ""),
        //Join the list with a space character between each item
        TextJoinList = Text.Combine(ListNonBlankValues," ")
    in
        TextJoinList,

It works perfectly fine and does what it should do but as soon as I replace the "test   test" with a reference to a column [Column1] it gives me this error:

Expression.Error: The import Combined matches no exports. Did you miss a module reference?

[jennratten]

What is the value and type of Column1?  Are there any nulls?  What happens if you pass null instead of "test test"?

[Anonymous]

It can be null and text. For null I made a special case: Combined = if text <> null then let ... else Combined = null

[jennratten · Accepted solution]

Yes, I see that in the function steps, however, did you test nulls?  What value and type is in Column 1?  The reason I ask is because when if statements are included in functions and the function is invoked, the behavior is slightly different than it would be if included outside of the function.