Fix incorrect attempted send_file deserialization

If http::send_file received a non-success status code due to reasons
such as sending to an invalid channel Id, not having permissions, or
sending too large of a file, then it would still try to deserialize
a response as if it were valid.

To fix this, ensure that the response is successful. Document that if
the file sent is too large, then
`HttpError::InvalidRequest(PayloadTooLarge)` is returned.

src/http/mod.rs

@@ -1370,6 +1370,14 @@ pub fn remove_group_recipient(group_id: u64, user_id: u64) -> Result<()> {
 }
 
 /// Sends a file to a channel.
+///
+/// # Errors
+///
+/// Returns an
+/// [`HttpError::InvalidRequest(PayloadTooLarge)`][`HttpError::InvalidRequest`]
+/// if the file is too large to send.
+///
+/// [`HttpError::InvalidRequest`]: enum.HttpError.html#variant.InvalidRequest
 pub fn send_file<R: Read>(channel_id: u64, mut file: R, filename: &str, map: JsonMap)
     -> Result<Message> {
     let uri = format!(api!("/channels/{}/messages"), channel_id);
@@ -1400,6 +1408,10 @@ pub fn send_file<R: Read>(channel_id: u64, mut file: R, filename: &str, map: Jso
 
     let response = request.send()?;
 
+    if response.status.class() != StatusClass::Success {
+        return Err(Error::Http(HttpError::InvalidRequest(response.status)));
+    }
+
     serde_json::from_reader::<HyperResponse, Message>(response).map_err(From::from)
 }
 

src/model/channel/channel_id.rs

@@ -382,6 +382,12 @@ impl ChannelId {
     /// [`ModelError::MessageTooLong`] will be returned, containing the number
     /// of unicode code points over the limit.
     ///
+    /// Returns an
+    /// [`HttpError::InvalidRequest(PayloadTooLarge)`][`HttpError::InvalidRequest`]
+    /// if the file is too large to send.
+    ///
+    ///
+    /// [`HttpError::InvalidRequest`]: ../http/enum.HttpError.html#variant.InvalidRequest
     /// [`ModelError::MessageTooLong`]: enum.ModelError.html#variant.MessageTooLong
     /// [`CreateMessage::content`]: ../builder/struct.CreateMessage.html#method.content
     /// [`GuildChannel`]: struct.GuildChannel.html

src/model/channel/group.rs

@@ -285,11 +285,16 @@ impl Group {
     ///
     /// # Errors
     ///
+    /// Returns an
+    /// [`HttpError::InvalidRequest(PayloadTooLarge)`][`HttpError::InvalidRequest`]
+    /// if the file is too large to send.
+    ///
     /// If the content of the message is over the above limit, then a
     /// [`ModelError::MessageTooLong`] will be returned, containing the number
     /// of unicode code points over the limit.
     ///
     /// [`ChannelId::send_file`]: struct.ChannelId.html#method.send_file
+    /// [`HttpError::InvalidRequest`]: ../http/enum.HttpError.html#variant.InvalidRequest
     /// [`ModelError::MessageTooLong`]: enum.ModelError.html#variant.MessageTooLong
     /// [Attach Files]: permissions/constant.ATTACH_FILES.html
     /// [Send Messages]: permissions/constant.SEND_MESSAGES.html

src/model/channel/guild_channel.rs

@@ -544,11 +544,16 @@ impl GuildChannel {
     ///
     /// # Errors
     ///
+    /// Returns an
+    /// [`HttpError::InvalidRequest(PayloadTooLarge)`][`HttpError::InvalidRequest`]
+    /// if the file is too large to send.
+    ///
     /// If the content of the message is over the above limit, then a
     /// [`ModelError::MessageTooLong`] will be returned, containing the number
     /// of unicode code points over the limit.
     ///
     /// [`ChannelId::send_file`]: struct.ChannelId.html#method.send_file
+    /// [`HttpError::InvalidRequest`]: ../http/enum.HttpError.html#variant.InvalidRequest
     /// [`ModelError::MessageTooLong`]: enum.ModelError.html#variant.MessageTooLong
     /// [Attach Files]: permissions/constant.ATTACH_FILES.html
     /// [Send Messages]: permissions/constant.SEND_MESSAGES.html

src/model/channel/mod.rs

@@ -280,11 +280,16 @@ impl Channel {
     ///
     /// # Errors
     ///
+    /// Returns an
+    /// [`HttpError::InvalidRequest(PayloadTooLarge)`][`HttpError::InvalidRequest`]
+    /// if the file is too large to send.
+    ///
     /// If the content of the message is over the above limit, then a
     /// [`ModelError::MessageTooLong`] will be returned, containing the number
     /// of unicode code points over the limit.
     ///
     /// [`ChannelId::send_file`]: struct.ChannelId.html#method.send_file
+    /// [`HttpError::InvalidRequest`]: ../http/enum.HttpError.html#variant.InvalidRequest
     /// [`ModelError::MessageTooLong`]: enum.ModelError.html#variant.MessageTooLong
     /// [Attach Files]: permissions/constant.ATTACH_FILES.html
     /// [Send Messages]: permissions/constant.SEND_MESSAGES.html

src/model/channel/private_channel.rs

@@ -231,11 +231,16 @@ impl PrivateChannel {
     ///
     /// # Errors
     ///
+    /// Returns an
+    /// [`HttpError::InvalidRequest(PayloadTooLarge)`][`HttpError::InvalidRequest`]
+    /// if the file is too large to send.
+    ///
     /// If the content of the message is over the above limit, then a
     /// [`ModelError::MessageTooLong`] will be returned, containing the number
     /// of unicode code points over the limit.
     ///
     /// [`ChannelId::send_file`]: struct.ChannelId.html#method.send_file
+    /// [`HttpError::InvalidRequest`]: ../http/enum.HttpError.html#variant.InvalidRequest
     /// [`ModelError::MessageTooLong`]: enum.ModelError.html#variant.MessageTooLong
     /// [Attach Files]: permissions/constant.ATTACH_FILES.html
     /// [Send Messages]: permissions/constant.SEND_MESSAGES.html