chore: raise errors instead of asserting on driver replies

Also fix the generator header and the roll skill, which still described
the params dicts.

Author: pavelfeldman

.claude/skills/playwright-roll/SKILL.md

@@ -261,7 +261,7 @@ Failure modes and fixes:
 | Symptom | Cause | Fix |
 |---|---|---|
 | mypy: `"XImpl" has no attribute "y"` in `_generated.py` | The docs have a new member `X.y`; `_impl/` does not. | PORT it. |
-| mypy: `Unexpected keyword argument "z" for "y" of "XImpl"` | New parameter or option on an existing method. | Add the parameter in `_impl/` under its Python (snake_case) name, as `Optional[X]` with no default, and put it in the params dict. mypy then reports each caller that must pass it. If Python must not have it, fix the docs: `* langs:` on the option. |
+| mypy: `Unexpected keyword argument "z" for "y" of "XImpl"` | New parameter or option on an existing method. | Add the parameter in `_impl/` under its Python (snake_case) name, as `Optional[X]` with no default, and pass it in the channel call. mypy then reports each caller that must pass it. If Python must not have it, fix the docs: `* langs:` on the option. |
 | mypy: `Missing named argument "z" for "y" of "XChannel"` | The protocol added a parameter to a command. | Pass the value in the channel call. If the implementation method needs a new parameter for it, add it as above. |
 | mypy: incompatible argument type in `_generated.py` | The docs type changed, or `_impl/` declares a narrower type. | Match the type in `_impl/`, or fix the docs with a Python-only declaration (`* langs: python`). |
 | generator: `No Python name for the struct at X.y.z` | A new inline `[Object]` with no name in the docs. | Name it in the docs: `` "Name" <[Object]> ``. |

playwright/_impl/_fetch.py

@@ -421,7 +421,8 @@ async def _inner_fetch(
         if max_retries is not None and max_retries < 0:
             raise Error("'max_retries' must be greater than or equal to '0'")
         url = url or (request.url if request else url)
-        assert url is not None
+        if url is None:
+            raise Error("url: expected a URL string or a Request")
         method = method or (request.method if request else "GET")
         # Cannot call allHeaders() here as the request may be paused inside route handler.
         headers_obj = headers or (request.headers if request else None)

playwright/_impl/_har_router.py

@@ -53,7 +53,8 @@ async def create(
         if result["error"]:
             raise Error(result["error"])
         har_id = result["harId"]
-        assert har_id
+        if har_id is None:
+            raise Error("harOpen returned no HAR id")
         return HarRouter(
             local_utils=local_utils,
             har_id=har_id,

playwright/_impl/_tracing.py

@@ -113,10 +113,12 @@ async def _do_stop_chunk(
 
         if is_local:
             result = await self._channel.tracingStopChunk(mode="entries")
-            assert result["entries"] is not None
+            entries = result["entries"]
+            if entries is None:
+                raise Error("tracingStopChunk returned no entries")
             await self._connection.local_utils.zip(
                 zip_file=str(file_path),
-                entries=result["entries"],
+                entries=entries,
                 stacks_id=self._stacks_id,
                 mode="write",
                 include_sources=self._include_sources,
@@ -246,10 +248,12 @@ async def _export_har(self, har_id: str) -> None:
             if not is_zip:
                 # Server wrote HAR and resources to the user's chosen paths.
                 return
-            assert result["entries"] is not None
+            entries = result["entries"]
+            if entries is None:
+                raise Error("harExport returned no entries")
             await self._connection.local_utils.zip(
                 zip_file=recorder["path"],
-                entries=result["entries"],
+                entries=entries,
                 stacks_id=None,
                 mode="write",
                 include_sources=False,
@@ -258,7 +262,8 @@ async def _export_har(self, har_id: str) -> None:
             return
 
         result = await self._channel.harExport(harId=har_id, mode="archive")
-        assert result["artifact"]
+        if result["artifact"] is None:
+            raise Error("harExport returned no artifact")
         artifact = cast(Artifact, from_channel(result["artifact"]))
         if is_zip:
             await artifact.save_as(recorder["path"])

scripts/codegen/generate_protocol.py

@@ -15,10 +15,12 @@
 # Generates from the protocol spec (packages/protocol/spec/*.yml in
 # microsoft/playwright):
 # - playwright/_impl/_protocol.py: the tables that _protocol_check.py uses;
-# - playwright/_impl/_protocol_types.py: a TypedDict for each message.
+# - playwright/_impl/_protocol_types.py: the TypedDicts of the messages;
+# - playwright/_impl/_protocol_channels.py: a typed channel class per interface.
 #
 # Usage:
-#   PW_SRC_DIR=<microsoft/playwright checkout> python scripts/codegen/generate_protocol.py --out <file> --types-out <file>
+#   PW_SRC_DIR=<microsoft/playwright checkout> python scripts/codegen/generate_protocol.py \
+#       --out <file> --types-out <file> --channels-out <file>
 #
 # The spec is loaded the same way as utils/protocol_spec.js does it. The output
 # is not formatted; run black on it.