Fix u32 parse panic in decode_csv

[smackysnacks]

This PR fixes an unhandled parsing error in decode_csv found with cargo fuzz. The following input no longer causes a panic:

<?xml version="1.0" encoding="UTF-8"?>
<map version="1.4" tiledversion="1.4.0" orientation="orthogonal" renderorder="right-down" width="100" height="100" tilewidth="32" tileheight="32" infinite="0" backgroundcolor="#ff00ff" nextlayerid="3" nextobjectid="5">
 <tileset firstgid="1" name="tilesheet" tilewidth="32" tileheight="32" tilecount="84" columns="14">
  <properties>
   <property name="tileset property" value="tsp"/>
  </properties>
  <image source="tilesheet.png" width="448" height="192"/>
  <tile id="1">
   <properties>
    <property name="a tile property" value="123"/>
   </properties>
  </tile>
 </tileset>
 <layer id="1" name="Tile Layer 1" width="100" height="100">
  <properties>
   <property name="prop1" value="12"/>
   <property name="prop2" value="some text"/>
   <property name="prop3">Line 1
Line 2
Line 3,
  etc
   </property>
  </properties>
  <data encoding="csv">
35,35,35,35,35,33,33,33,33,33,33,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
 </objectgroup>
</map>

[aleokdev]

Many thanks!

[aleokdev]

I'd prefer that this were an error type so the user could handle it (or format it some other way) if necessary

[smackysnacks]

I think we have several options here. One option would be

CsvDecodingError(Box<dyn std::error::Error + Send + Sync + 'static>)

Alternatively, we could do something like

/// Errors that can occur while decoding csv data.
#[derive(Clone, Debug, PartialEq, Eq)]
pub enum CsvError {
    TileDataParseError(ParseIntError)
}

/// Errors which occurred when parsing the file
#[derive(Debug)]
#[non_exhaustive]
pub enum Error {
<SNIP>
    /// An error occurred when decoding a csv encoded dataset.
    CsvDecodingError(CsvError),

Do you have a preference?

[aleokdev]

Second one looks better IMO: Lets you look into the error, like in the other enum variants.

[aleokdev]

LGTM!

[aleokdev]

I forgot to check for the changelog again x_x I'll update it when the version gets released I guess

[bjorn]

@aleokdev Heh, we should probably look into adding a workflow warning about this. :D

[aleokdev]

I have one set up for another project as a GH action, I'll look into importing it whenever possible if you'd like.