Invalid map format handling

pytiled_parser/parser.py

@@ -21,9 +21,11 @@ def parse_map(file: Path) -> TiledMap:
     # The type ignores are because mypy for some reason thinks those functions return Any
     if parser == "tmx":
         return tmx_map_parse(file)  # type: ignore
-    elif parser == "json":
-        return json_map_parse(file)  # type: ignore
     else:
-        raise UnknownFormat(
-            "Unknown Map Format, please use either the TMX or JSON format."
-        )
+        try:
+            return json_map_parse(file)  # type: ignore
+        except ValueError:
+            raise UnknownFormat(
+                "Unknown Map Format, please use either the TMX or JSON format. "
+                "This message could also mean your map file is invalid or corrupted."
+            )

tests/test_data/invalid_format.garbage

@@ -0,0 +1 @@
+|thisissomegarbageformat||||ohmylookhowbaditis||thiswillcertainlybreakthigns|||

tests/test_invalid_format.py

@@ -0,0 +1,13 @@
+import os
+from pathlib import Path
+
+import pytest
+
+from pytiled_parser import UnknownFormat, parse_map
+
+TESTS_DIR = Path(os.path.dirname(os.path.abspath(__file__)))
+MAP_FILE = TESTS_DIR / "test_data/invalid_format.garbage"
+
+def test_map_invalid_format():
+    with pytest.raises(UnknownFormat) as e:
+        parse_map(MAP_FILE)