flutter compile time conditional

Question

i've added a background isolate and it works fine on macOs and android, but as soon as i flutter run -d chrome i.e. compile for web i get a compile time error:

[...] Error: Member not found:
'BackgroundIsolateBinaryMessenger.ensureInitialized'.
    BackgroundIsolateBinaryMessenger.ensureInitialized(input.rootIsolateToken);
                                     ^^^^^^^^^^^^^^^^^

which makes sense since that's not supported in web

but how can i omit this when compiling for web, i tried this but it wont work:

if (!kIsWeb) {
    // Register the background isolate with the root isolate.
    // comiler still unhappy that this member doenst exist, but it should simply skip this block 
    BackgroundIsolateBinaryMessenger.ensureInitialized(input.rootIsolateToken);
}

i'm looking for a solution similar to C's #if, #endif

is this a flutter bug or am i supposed to wrap the BackGroundIsolateBinaryMessenger in my own lib like described in this answer?

or can i somehow mark the if statement as const s.t. it gets evaluated at compile time?