chore: validate dictionary keys

[pavelfeldman]

No description provided.

[coveralls]

Pull Request Test Coverage Report for Build 194383153

• 167 of 174 (95.98%) changed or added relevant lines in 14 files are covered.
• 16 unchanged lines in 7 files lost coverage.
• Overall coverage decreased (-0.1%) to 88.776%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
playwright/browser_type.py	12	19	63.16%

Files with Coverage Reduction	New Missed Lines	%
playwright/browser_type.py	1	65.38%
playwright/object_factory.py	1	98.53%
playwright/async_api.py	2	90.6%
playwright/connection.py	2	97.02%
playwright/sync_api.py	2	67.81%
playwright/sync_base.py	3	93.33%
playwright/main.py	5	82.19%

Totals
Change from base Build 194173457:	-0.1%
Covered Lines:	3575
Relevant Lines:	4027

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 195303243

• 177 of 183 (96.72%) changed or added relevant lines in 14 files are covered.
• 2 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.1%) to 89.604%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
scripts/documentation_provider.py	105	106	99.06%
playwright/browser_type.py	14	19	73.68%

Files with Coverage Reduction	New Missed Lines	%
playwright/browser_type.py	1	74.07%
playwright/connection.py	1	97.62%

Totals
Change from base Build 195249552:	0.1%
Covered Lines:	3620
Relevant Lines:	4040

---

💛 - Coveralls

[mxschmitt]

great work!