f1dad0bcb5
We previously assumed that every `DW_AT_LLVM_stmt_sequence` attribute has a corresponding sequence in the processed line table. However, this isn't always true. Some sequences can be removed by the linker if they are empty, as shown [here](https://github.com/alx32/llvm-project/blob/release/14.x/llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp#L565-L566). When an attribute refers to one of these removed sequences, there is no actual sequence for it to match. In such cases, we update the attribute to indicate that it is invalid and does not point to any sequence. This informs readers that the attribute should be ignored. The newly modified test would have triggered the assert that is being removed in this patch.