[perl #128402] [LTA] Only a line number is printed when assigning to immutable values (stuff; $x = 42; stuff)

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# New Ticket Created by  Alex Jakimenko 
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Code:
my $x := 42;
my $a = 4 + 8; $x = 24; my $b = 15 + 16;


Result:
Cannot assign to an immutable value
  in block <unit> at foo.p6 line 2


Line 2, right, but where exactly? Surely it can also print the cursor position 
or something.