fix(proto): fix optional repeated field generation (#24)

- Fixed broken protobuf generation when using `optional` with `repeated` fields
- Added `unwrap_or_default()` to handle missing values safely
- Included missing `break` to prevent logic errors during parsing
- Pushed final changeset for consistent behavior

Author: CanardMandarin

.changeset/fix-optional-repeated-protobuf.md

@@ -0,0 +1,5 @@
+---
+"@codama/renderers-vixen-parser": patch
+---
+
+- Fix broken protobuf generation for optional vectors in IDL.

src/getProtoTypeManifestVisitor.ts

@@ -304,6 +304,9 @@ export function getProtoTypeManifestVisitor(options: {
 
                     const optionPrefix = resolveNestedTypeNode(optionType.prefix);
                     if (optionPrefix.format === 'u8' && optionPrefix.endian === 'le') {
+                        if (childManifest.type.startsWith('repeated ')) {
+                            return childManifest;
+                        }
                         return {
                             ...childManifest,
                             type: `optional ${childManifest.type}`,

src/getRenderMapVisitor.ts

@@ -209,14 +209,24 @@ function getOptionTypeTransform(
     const innerTransform = getTransform(item, outerTypeName, idlDefinedTypes, options);
     const cleanedTransform = innerTransform.replace(`self.${outerTypeName}`, 'x');
 
+    let returnTransform = '';
     switch (cleanedTransform) {
         case 'x':
-            return `self.${outerTypeName}`;
+            returnTransform = `self.${outerTypeName}`;
+            break;
         case 'Some(x.into_proto())':
-            return `self.${outerTypeName}.map(|x| x.into_proto())`;
+            returnTransform = `self.${outerTypeName}.map(|x| x.into_proto())`;
+            break;
         default:
-            return `self.${outerTypeName}.map(|x| ${cleanedTransform})`;
+            returnTransform = `self.${outerTypeName}.map(|x| ${cleanedTransform})`;
+            break;
     }
+
+    if (item.kind === 'arrayTypeNode' || item.kind === 'fixedSizeTypeNode') {
+        returnTransform += '.unwrap_or_default()';
+    }
+
+    return returnTransform;
 }
 
 function getTransform(