Fix a bug in check-local-exists elision

kernel/modelverse_jit/cfg_optimization.py

@@ -132,6 +132,7 @@ def elide_local_checks(entry_point):
                 if dominator_tree.dominates_instruction(local_def, check):
                     # Check is dominated by a definition. Replace it by a 'True' literal.
                     check.redefine(cfg_ir.Literal(True))
+                    is_reachable = True
                     break
                 elif check.block in reachable_blocks[local_def.block]:
                     is_reachable = True