return typed errors when parsing the user module

dan_layer/template_macros/src/ast.rs

@@ -24,6 +24,7 @@ use syn::{
     parse::{Parse, ParseStream},
     punctuated::Punctuated,
     token::Comma,
+    Error,
     FnArg,
     Ident,
     ImplItem,
@@ -51,24 +52,24 @@ impl Parse for TemplateAst {
         // get the contents of the "mod" block
         let items = match module.content {
             Some((_, items)) => items,
-            None => panic!("empty module"),
+            None => return Err(Error::new(module.ident.span(), "empty module")),
         };
 
         // there should be two items: the "struct" and the "impl" blocks
         if items.len() != 2 {
-            panic!("invalid number of module sections");
+            return Err(Error::new(module.ident.span(), "invalid number of module sections"));
         }
 
         // get the "struct" block
         let struct_section = match &items[0] {
             syn::Item::Struct(struct_item) => struct_item.clone(),
-            _ => panic!("the first section is not a 'struct'"),
+            _ => return Err(Error::new(module.ident.span(), "the first section is not a 'struct'")),
         };
 
         // get the "impl" block
         let impl_section = match &items[1] {
             syn::Item::Impl(impl_item) => impl_item.clone(),
-            _ => panic!("the second section is not an 'impl'"),
+            _ => return Err(Error::new(module.ident.span(), "the second section is not an 'impl'")),
         };
 
         let template_name = struct_section.ident.clone();