Render recipe even when there're frontmatter YAML syntax issues

src/analysis/event_consumer.rs

@@ -228,14 +228,15 @@ impl<'i> RecipeCollector<'i, '_> {
             Err(err) => {
                 // ! This message (can) contains line and column number, but line numbers
                 // ! are off by one thanks to the starting `---`
-                let mut diag = error!(err.to_string());
+                let mut diag = warning!(format!("Invalid YAML frontmatter syntax: {}", err));
                 let err_span = err
                     .location()
                     .map(|loc| Span::pos(yaml_text.span().start() + loc.index()));
                 if let Some(loc) = err_span {
                     diag = diag.label(label!(loc));
                 }
-                self.ctx.error(diag);
+                diag.add_hint("The frontmatter will be ignored. Fix the YAML syntax to use metadata.");
+                self.ctx.warn(diag);
                 return;
             }
         };

tests/frontmatter_tests.rs

@@ -0,0 +1,140 @@
+use cooklang;
+use indoc::indoc;
+
+#[test]
+fn test_invalid_yaml_frontmatter_becomes_warning() {
+    let input = indoc! {r#"
+        ---
+        title: Test Recipe
+        tags: [test
+        invalid yaml here
+        ---
+
+        This is a test recipe with invalid YAML frontmatter.
+
+        @eggs{2} and @butter{1%tbsp}
+    "#};
+
+    let result = cooklang::parse(input);
+
+    // Should not fail to parse
+    assert!(result.output().is_some(), "Recipe should parse successfully despite invalid YAML");
+
+    let recipe = result.output().unwrap();
+    let warnings = result.report();
+
+    // Should have warnings about invalid YAML
+    assert!(!warnings.is_empty(), "Should have warnings about invalid YAML");
+
+    // The frontmatter should be ignored, so metadata should be empty
+    assert!(recipe.metadata.map.is_empty(), "Metadata should be empty when YAML is invalid");
+
+    // Should still parse the recipe content
+    assert_eq!(recipe.ingredients.len(), 2, "Should still parse ingredients");
+    assert_eq!(recipe.ingredients[0].name, "eggs");
+    assert_eq!(recipe.ingredients[1].name, "butter");
+}
+
+#[test]
+fn test_valid_yaml_frontmatter_still_works() {
+    let input = indoc! {r#"
+        ---
+        title: Test Recipe
+        tags: [test, recipe]
+        prep_time: 10 min
+        ---
+
+        This is a test recipe with valid YAML frontmatter.
+
+        @eggs{2} and @butter{1%tbsp}
+    "#};
+
+    let result = cooklang::parse(input);
+
+    // Should parse successfully
+    assert!(result.output().is_some(), "Recipe should parse successfully");
+
+    let recipe = result.output().unwrap();
+
+    // Metadata should be parsed
+    assert!(!recipe.metadata.map.is_empty(), "Metadata should not be empty");
+    assert_eq!(
+        recipe.metadata.map.get("title").and_then(|v| v.as_str()),
+        Some("Test Recipe"),
+        "Title should be parsed correctly"
+    );
+
+    // Should still parse the recipe content
+    assert_eq!(recipe.ingredients.len(), 2, "Should parse ingredients");
+    assert_eq!(recipe.ingredients[0].name, "eggs");
+    assert_eq!(recipe.ingredients[1].name, "butter");
+}
+
+#[test]
+fn test_invalid_yaml_with_colon_in_value() {
+    let input = indoc! {r#"
+        ---
+        title: Recipe: with colon
+        description: This has: many: colons
+        tags: [unclosed
+        ---
+
+        @flour{2%cups}
+    "#};
+
+    let result = cooklang::parse(input);
+
+    // Should not fail to parse
+    assert!(result.output().is_some(), "Recipe should parse successfully despite invalid YAML");
+
+    let recipe = result.output().unwrap();
+    let warnings = result.report();
+
+    // Should have warnings
+    assert!(!warnings.is_empty(), "Should have warnings about invalid YAML");
+
+    // Metadata should be empty due to invalid YAML
+    assert!(recipe.metadata.map.is_empty(), "Metadata should be empty when YAML is invalid");
+
+    // Should still parse ingredients
+    assert_eq!(recipe.ingredients.len(), 1);
+    assert_eq!(recipe.ingredients[0].name, "flour");
+}
+
+#[test]
+fn test_completely_malformed_yaml() {
+    let input = indoc! {r#"
+        ---
+        { this is not valid yaml at all }}}
+        : : : :
+        ---
+
+        Simple recipe with @salt and @pepper
+    "#};
+
+    let result = cooklang::parse(input);
+
+    // Should not fail to parse
+    assert!(result.output().is_some(), "Recipe should parse successfully despite malformed YAML");
+
+    let recipe = result.output().unwrap();
+    let warnings = result.report();
+
+    // Should have warnings
+    assert!(!warnings.is_empty(), "Should have warnings about invalid YAML");
+
+    // Should contain information about invalid YAML in warning
+    let warning_str = format!("{:?}", warnings);
+    assert!(
+        warning_str.contains("Invalid YAML") || warning_str.contains("invalid YAML"),
+        "Warning should mention invalid YAML"
+    );
+
+    // Metadata should be empty
+    assert!(recipe.metadata.map.is_empty(), "Metadata should be empty when YAML is invalid");
+
+    // Should still parse the recipe
+    assert_eq!(recipe.ingredients.len(), 2);
+    assert_eq!(recipe.ingredients[0].name, "salt");
+    assert_eq!(recipe.ingredients[1].name, "pepper");
+}