refactor! split SubplotError::IoError into more specific errors

Replace SubplotError::IoError with ::Spawn, ::WriteToChild,
::WaitForChild, ::ReadFile, ::CreateFile, ::Writefile.

IoError was a catchall error and as such, so generic that it didn't
help the user to figure out what actually is wrong. For example, there
was no indication what operation was attempted or on what file. The
new error variants are specific.

Sponsored-by: author

1 files changed, 2 insertions, 1 deletions

diff --git a/src/doc.rs b/src/doc.rs
index e65aff5..37f32d6 100644
--- a/src/doc.rs
+++ b/src/doc.rs
@@ -204,7 +204,8 @@ impl<'a> Document {
     ) -> Result<Document, SubplotError> {
         trace!("Parsing document with pullmark-cmark from {:?}", filename);
         let filename = filename.to_path_buf();
-        let markdown = std::fs::read_to_string(&filename)?;
+        let markdown = std::fs::read_to_string(&filename)
+            .map_err(|err| SubplotError::ReadFile(filename.clone(), err))?;
         let ast = ast::AbstractSyntaxTree::from_str(&markdown)?;
 
         trace!("Parsed document OK");