SNOW-3385961: improve INFER_SCHEMA zero-row FileNotFoundError message

When INFER_SCHEMA returns zero rows, the reader used to raise:

    FileNotFoundError: Given path: '{path}' could not be found or is empty.

Zero rows can also mean file-format options silently filtered every
row/header (e.g. PARSE_HEADER on a file with a leading blank line,
SKIP_HEADER exceeding row count, or ON_ERROR=CONTINUE dropping bad
rows). The old message sends users chasing a path-not-found issue
that isn't real.

Keep the exception type (FileNotFoundError) for back-compat, but
rewrite the message to surface both possibilities and append any
applied PARSE_HEADER / SKIP_HEADER / ON_ERROR values that are already
in scope (no extra round-trip).

Update the existing integ assertions in test_filepath_not_exist_or_empty
to match the new wording and to access the message via str(ex_info.value)
so the full (longer) message is compared.

Author: sfc-gh-fhe

src/snowflake/snowpark/dataframe_reader.py

@@ -1338,8 +1338,31 @@ def _infer_schema_for_file_format(
                     raise e
 
             if len(results) == 0:
+                # Zero rows from INFER_SCHEMA can mean the path is empty/missing,
+                # or that file format options silently filtered every row/header
+                # (e.g. PARSE_HEADER on a file with a leading blank line,
+                # SKIP_HEADER exceeding row count, or ON_ERROR=CONTINUE dropping
+                # bad rows). Surface both possibilities so callers don't chase a
+                # phantom path-not-found issue when the real cause is a format
+                # option.
+                option_hints = []
+                for key in ("PARSE_HEADER", "SKIP_HEADER", "ON_ERROR"):
+                    if key in format_type_options:
+                        option_hints.append(f"{key}={format_type_options[key]}")
+                    elif key in infer_schema_options:
+                        option_hints.append(f"{key}={infer_schema_options[key]}")
+                hint_suffix = (
+                    f" Applied file format options: {', '.join(option_hints)}."
+                    if option_hints
+                    else ""
+                )
                 raise FileNotFoundError(
-                    f"Given path: '{path}' could not be found or is empty."
+                    f"Given path: '{path}' returned no results from INFER_SCHEMA. "
+                    "The path may be empty or missing, or file format options may "
+                    "have filtered every row/header (e.g. PARSE_HEADER on a file "
+                    "with a leading blank line, SKIP_HEADER exceeding row count, "
+                    "or ON_ERROR=CONTINUE silently dropping bad rows). Check the "
+                    "file contents and file format options." + hint_suffix
                 )
             new_schema = []
             schema_to_cast = []

tests/integ/scala/test_dataframe_reader_suite.py

@@ -2119,18 +2119,23 @@ def test_filepath_not_exist_or_empty(session):
         session.read.option("PARSE_HEADER", True).option("INFER_SCHEMA", True).csv(
             empty_file_path
         )
-    assert f"Given path: '{empty_file_path}' could not be found or is empty." in str(
-        ex_info
+    assert (
+        f"Given path: '{empty_file_path}' returned no results from INFER_SCHEMA."
+        in str(ex_info.value)
     )
+    # Message should mention file format options so users don't chase a phantom
+    # path-not-found when the real cause is PARSE_HEADER/SKIP_HEADER/ON_ERROR.
+    assert "file format options" in str(ex_info.value)
 
     with pytest.raises(FileNotFoundError) as ex_info:
         session.read.option("PARSE_HEADER", True).option("INFER_SCHEMA", True).csv(
             not_exist_file_path
         )
     assert (
-        f"Given path: '{not_exist_file_path}' could not be found or is empty."
-        in str(ex_info)
+        f"Given path: '{not_exist_file_path}' returned no results from INFER_SCHEMA."
+        in str(ex_info.value)
     )
+    assert "file format options" in str(ex_info.value)
 
 
 @pytest.mark.skipif(