Remaining bare `except:` / swallowed exceptions in tests/ and src/ (Codacy + hidden failures)

[petercorke]

Follow-up to #51 / #114, which fixed the bare except: pass pattern in tests/test_image_point_features.py. Inventory of what remains as of 2026-10-03 (main at 770a031). These are likely contributing to the Codacy B grade (Pylint/Pyflakes bare-except and try/except/pass/W0702/W0703-type findings, see #41) and, in tests, hide real failures.

Why it matters

In tests, a bare except: also swallows the AssertionError from assert*, so the test can never fail. Fixing the same pattern in #114 showed that several of those tests had been calling APIs that don't exist (Image.SURF, corners, getpixel, concat), so expect similar findings here: fix by running each snippet unprotected on OpenCV 4 and 5, rewriting against the real API with direct assertions, and mutation-checking that the test now fails when the code is broken (see #114's PR description for the method).

tests/

File	bare except:	except Exception + pass/continue
tests/test_camera.py	11	8
tests/base/test_base_color.py	3	1
tests/test_ros.py	0	3
tests/conftest.py	0	2 (probably legitimate GUI-suppression; review rather than blanket-remove)

src/

Location	Issue	Suggested fix
base/color.py:966 and :976 (rgb2xyz-style white/primaries lookup)	bare except: around a dict lookup, then raise ValueError("unknown white value, must be one of" ", ".join(...)). Real bug: the two adjacent string literals concatenate first, so ", ".join(...) uses the whole sentence as the separator; the error message is garbled.	except KeyError: and build the message with an f-string: f"unknown white value, must be one of {', '.join(_whites)}", plus a test that checks the message
base/findpeaks.py:119	bare except: around Polynomial.fit, then print + continue	catch the specific exceptions Polynomial.fit raises for a neighbourhood falling off the data; use warnings.warn rather than print
base/imageio.py:1033 (set_window_title)	bare except: pass	except (AttributeError, RuntimeError): (backends without a window manager)
Camera.py, ImageProcessing.py, base/imageio.py	one except Exception: pass/continue each	review each: narrow the exception type or log

Suggested approach

Separate small PRs: (1) color.py message bug + test (src, real fix), (2) other src sites, (3) tests/test_camera.py, (4) tests/base/test_base_color.py and the rest. Add E722 (bare except) and BLE001/S110 (try-except-pass) to the ruff rule set once clean so it can't regress (see the typing/lint cluster, #40/#41).

Related: #41, #51, #113