Improve error handling in compare.

src/compare/diff.rs

@@ -66,7 +66,6 @@ use crate::parser::VerseBlock;
 pub struct DiffResult {
     status: DiffStatus,
     name: String,
-    #[allow(dead_code)]
     message: Option<String>,
     children: Vec<DiffResult>,
 }
@@ -178,7 +177,7 @@ fn compare_element<'s>(
     emacs: &'s Token<'s>,
     rust: &'s Element<'s>,
 ) -> Result<DiffResult, Box<dyn std::error::Error>> {
-    match rust {
+    let compare_result = match rust {
         Element::Paragraph(obj) => compare_paragraph(source, emacs, obj),
         Element::PlainList(obj) => compare_plain_list(source, emacs, obj),
         Element::GreaterBlock(obj) => compare_greater_block(source, emacs, obj),
@@ -200,6 +199,15 @@ fn compare_element<'s>(
         Element::HorizontalRule(obj) => compare_horizontal_rule(source, emacs, obj),
         Element::Keyword(obj) => compare_keyword(source, emacs, obj),
         Element::LatexEnvironment(obj) => compare_latex_environment(source, emacs, obj),
+    };
+    match compare_result {
+        Ok(_) => compare_result,
+        Err(ref e) => Ok(DiffResult {
+            status: DiffStatus::Bad,
+            name: "error!".to_owned(),
+            message: Some(e.to_string()),
+            children: Vec::new(),
+        }),
     }
 }
 
@@ -208,7 +216,7 @@ fn compare_object<'s>(
     emacs: &'s Token<'s>,
     rust: &'s Object<'s>,
 ) -> Result<DiffResult, Box<dyn std::error::Error>> {
-    match rust {
+    let compare_result = match rust {
         Object::Bold(obj) => compare_bold(source, emacs, obj),
         Object::Italic(obj) => compare_italic(source, emacs, obj),
         Object::Underline(obj) => compare_underline(source, emacs, obj),
@@ -236,6 +244,15 @@ fn compare_object<'s>(
         Object::Subscript(obj) => compare_subscript(source, emacs, obj),
         Object::Superscript(obj) => compare_superscript(source, emacs, obj),
         Object::Timestamp(obj) => compare_timestamp(source, emacs, obj),
+    };
+    match compare_result {
+        Ok(_) => compare_result,
+        Err(ref e) => Ok(DiffResult {
+            status: DiffStatus::Bad,
+            name: "error!".to_owned(),
+            message: Some(e.to_string()),
+            children: Vec::new(),
+        }),
     }
 }