"if static_label" in struct returns invalid label name

[Ladida4842]

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!rb as2
e = 1
struct aaaaa
if e
endif
endstruct

this returns:

Errors occurred while assembling.
<input>:4: error: (Einvalid_label_name): Invalid label name.
    in block: [if e]

given that static labels are supposed to work as "constants" this makes it a bit inconvenient