improve config.toml error msg (#1155)

improve config.toml error msg

when I write a unvalid config.toml
```toml
[[sources]]
# name = "company-internal"
url = "https://company.internal/simple/"
```
the before msg is very strange: `error: expected name`
after: `error: bad config.toml syntax,expected source.name`

rye/src/config.rs

@@ -232,7 +232,8 @@ impl Config {
  if let Some(sources) = self.doc.get("sources").map(|x| toml::iter_tables(x)) {
  for source in sources {
  let source = source.context("invalid value for source in config.toml")?;
- let source_ref = SourceRef::from_toml_table(source)?;
+ let source_ref = SourceRef::from_toml_table(source)
+ .context("invalid source definition in config.toml")?;
  if source_ref.name == "default" {
  need_default = false;
  }

rye/src/pyproject.rs

@@ -152,12 +152,12 @@ impl SourceRef {
  .get("name")
  .and_then(|x| x.as_str())
  .map(|x| x.to_string())
- .ok_or_else(|| anyhow!("expected name"))?;
+ .ok_or_else(|| anyhow!("expected source.name"))?;
  let url = source
  .get("url")
  .and_then(|x| x.as_str())
  .map(|x| x.to_string())
- .ok_or_else(|| anyhow!("expected url"))?;
+ .ok_or_else(|| anyhow!("expected source.url"))?;
  let verify_ssl = source
  .get("verify_ssl")
  .and_then(|x| x.as_bool())
@@ -174,7 +174,7 @@ impl SourceRef {
  .get("type")
  .and_then(|x| x.as_str())
  .map_or(Ok(SourceRefType::Index), |x| x.parse::<SourceRefType>())
- .context("invalid value for type")?;
+ .context("invalid value for source.type")?;
  Ok(SourceRef {
  name,
  url,
@@ -1265,7 +1265,8 @@ fn get_sources(doc: &DocumentMut) -> Result<Vec<SourceRef>, Error> {
  {
  for source in sources {
  let source = source.context("invalid value for pyproject.toml's tool.rye.sources")?;
- let source_ref = SourceRef::from_toml_table(source)?;
+ let source_ref = SourceRef::from_toml_table(source)
+ .context("invalid source definition in pyproject.toml")?;
  rv.push(source_ref);
  }
  }
@@ -1320,6 +1321,7 @@ fn get_project_metadata(path: &Path) -> Result<Metadata, Error> {
  }
  serde_json::from_slice(&metadata.stdout).map_err(Into::into)
 }
+
 /// Represents expanded sources.
 #[derive(Debug, Clone, Serialize)]
 pub struct ExpandedSources {