cmds / lib: Fix more static checker findings

Fix more errors and warnings produced by "make check" as reported by CI and a pyright upgrade.
Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/pkg/lib/FileContext.py

@@ -177,10 +177,10 @@ class FileContext(abc.ABC):
     ) -> Result:
         mode_str = None if mode is None else oct(mode).replace('0o', '0')
         if self.__out_pipe is not None:
-            result = await self.__out_pipe.run(content)
+            content = (await self.__out_pipe.run(content)).stdout
         return await self._put(
             self._chroot(path),
-            result.stdout,
+            content,
             wd = wd,
             throw = throw,
             verbose = verbose,