Raise helpful errors for missing compiler contexts

[harsh21234i]

Fixes #7489.

PageContext.get() and CompileContext.get() now raise descriptive RuntimeErrors when called outside page compilation or compilation, instead of exposing the raw ContextVar LookupError. Other BaseContext subclasses retain their existing LookupError behavior.

Adds regression tests and a reflex-base bugfix news fragment.

Validation: 47 focused tests passed; Ruff and Pyright passed.

[cubic-dev-ai]

No issues found across 4 files

_{View guided diff | Re-trigger cubic}

[greptile-apps]

Confidence Score: 5/5

[Medium impact] The PR appears safe to merge; the clearer errors preserve the original exception type.

Summary

Adds helpful errors when PageContext.get() or CompileContext.get() is called outside compilation.

• Keeps LookupError, preserving the original exception type.
• Leaves other context classes’ missing-context behavior unchanged.
• Adds message checks and a bugfix news fragment.
• No new actionable issues found. Tests were inspected, not run.

_{Reviews (2) · Last reviewed commit: "Preserve LookupError for compiler contex..." · Reviewed by Greptile}

[codspeed]

Merging this PR will degrade performance by 7.51%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

❌ 2 regressed benchmarks
✅ 148 untouched benchmarks
⏩ 18 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	test_hydration_metadata[200]	1.9 ms	2.1 ms	-9.46%
❌	test_hydration_metadata[20]	220.5 µs	233.4 µs	-5.53%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing harsh21234i:fix/7489-context-outside-compile (a9a7cb9) with main (deea1c3)}

Footnotes

1. 18 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩