generate_pcd example stops in a debugger and uses undefined rgbd

[dajiaohuang]

What happened

examples/python/generate_pcd.py currently calls reader.load_both(), discards the returned frames, enters an ipdb breakpoint, and then continues to use rgbd. Because rgbd is never assigned, the example cannot progress beyond the first frame in a normal run.

This is present on main at da721695829a0e947930f9b7f1a254dd695fb794.

Reproduction

$ uvx ruff check --no-cache --select F821 --output-format concise examples/python/generate_pcd.py
examples/python/generate_pcd.py:114:102: F821 Undefined name `rgbd`
examples/python/generate_pcd.py:117:20: F821 Undefined name `rgbd`
examples/python/generate_pcd.py:125:21: F821 Undefined name `rgbd`
examples/python/generate_pcd.py:129:32: F821 Undefined name `rgbd`
examples/python/generate_pcd.py:146:41: F821 Undefined name `rgbd`
examples/python/generate_pcd.py:157:56: F821 Undefined name `rgbd`
Found 6 errors.

Expected behavior

The example should load an RGBD frame into rgbd and run without an unconditional interactive debugger breakpoint.