[core] Catch body-read errors in download_content (#16023)

esphome/external_files.py

@@ -175,6 +175,11 @@ def download_content(url: str, path: Path, timeout: int = NETWORK_TIMEOUT) -> by
             headers={"User-agent": f"ESPHome/{__version__} (https://esphome.io)"},
         )
         req.raise_for_status()
+        # `.content` reads the body lazily; chunked-decode, gzip-decode,
+        # and mid-stream connection errors all surface here as
+        # RequestException subclasses, so this needs the same fall-back
+        # treatment as the request itself.
+        data = req.content
     except requests.exceptions.RequestException as e:
         if path.exists():
             _LOGGER.warning(
@@ -185,7 +190,6 @@ def download_content(url: str, path: Path, timeout: int = NETWORK_TIMEOUT) -> by
             return path.read_bytes()
         raise cv.Invalid(f"Could not download from {url}: {e}") from e
 
-    data = req.content
     write_file(path, data)
     _write_etag(path, req.headers.get(ETAG))
     return data