Fix bug introduced by #9386

[smoelius]

#9386 introduced a potential out-of-bounds array access. Specifically, a location returned by local_assignments could have location.statement_index equal to mir.basic_blocks[location.block].statements.len(), in which case the location would refer to the block terminator:

rust-clippy/clippy_lints/src/dereference.rs

Lines 1204 to 1206 in b8a9a50

	&& let [location] = *local_assignments(mir, local).as_slice()
	&& let StatementKind::Assign(box (_, Rvalue::Ref(_, _, place))) =
	mir.basic_blocks[location.block].statements[location.statement_index].kind

I suspect the bug is not triggerable now, because of checks leading up to where it occurs. But a future code change could make it triggerable. Hence, it should be fixed.

r? @Jarcho

changelog: none

[Jarcho]

Thank you. @bors r+

[bors]

📌 Commit 524ec2e has been approved by Jarcho

It is now in the queue for this repository.

[bors]

⌛ Testing commit 524ec2e with merge 967f172...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: Jarcho
Pushing 967f172 to master...