fix: disallow tileset width/height from being 0

Fixes a divide by zero panic

src/error.rs

@@ -1,3 +1,4 @@
+use crate::InvalidTilesetError::InvalidTileDimensions;
 use std::num::ParseIntError;
 use std::{fmt, path::PathBuf};
 
@@ -19,6 +20,27 @@ impl fmt::Display for CsvDecodingError {
 
 impl std::error::Error for CsvDecodingError {}
 
+/// Errors that can occur parsing a Tileset.
+#[derive(Clone, Debug, PartialEq, Eq)]
+#[non_exhaustive]
+pub enum InvalidTilesetError {
+    /// An invalid width or height (0) dimension was found in the input.
+    InvalidTileDimensions,
+}
+
+impl fmt::Display for InvalidTilesetError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            InvalidTileDimensions => write!(
+                f,
+                "An invalid width or height (0) dimension was found in the input."
+            ),
+        }
+    }
+}
+
+impl std::error::Error for InvalidTilesetError {}
+
 /// Errors which occurred when parsing the file
 #[derive(Debug)]
 #[non_exhaustive]
@@ -78,6 +100,8 @@ pub enum Error {
         /// Stores the wrongly parsed String.
         read_string: String,
     },
+    /// There was an invalid tileset in the map parsed.
+    InvalidTileset(InvalidTilesetError),
 }
 
 /// A result with an error variant of [`crate::Error`].
@@ -126,6 +150,7 @@ impl fmt::Display for Error {
             Error::TemplateHasNoObject => write!(fmt, "A template was found with no object element"),
             Error::InvalidWangIdEncoding{read_string} =>
                 write!(fmt, "\"{}\" is not a valid WangId format", read_string),
+            Error::InvalidTileset(e) => write!(fmt, "{}", e),
         }
     }
 }

src/tileset.rs

@@ -7,7 +7,7 @@ use crate::error::{Error, Result};
 use crate::image::Image;
 use crate::properties::{parse_properties, Properties};
 use crate::tile::TileData;
-use crate::{util::*, Gid, ResourceCache, ResourceReader, Tile, TileId};
+use crate::{util::*, Gid, InvalidTilesetError, ResourceCache, ResourceReader, Tile, TileId};
 
 mod wangset;
 pub use wangset::*;
@@ -153,6 +153,12 @@ impl Tileset {
            ((spacing, margin, columns, name, user_type, user_class), (tilecount, first_gid, tile_width, tile_height))
         );
 
+        if tile_width == 0 || tile_height == 0 {
+            return Err(Error::InvalidTileset(
+                InvalidTilesetError::InvalidTileDimensions,
+            ));
+        }
+
         let root_path = path.parent().ok_or(Error::PathIsNotFile)?.to_owned();
 
         Self::finish_parsing_xml(
@@ -223,6 +229,12 @@ impl Tileset {
             ((spacing, margin, columns, name, user_type, user_class), (tilecount, tile_width, tile_height))
         );
 
+        if tile_width == 0 || tile_height == 0 {
+            return Err(Error::InvalidTileset(
+                InvalidTilesetError::InvalidTileDimensions,
+            ));
+        }
+
         let root_path = path.parent().ok_or(Error::PathIsNotFile)?.to_owned();
 
         Self::finish_parsing_xml(