fix: replace assert! in AcceptHeader::new with Result

The assert! panicked at runtime when OpenAPI specs had endpoints with
empty content type strings. AcceptHeader::new now returns Result<Self>
like all other validated newtypes in the codebase.

Author: benaiad

crates/sqlize-core/src/catalog/ddl.rs

@@ -114,7 +114,7 @@ mod tests {
                 method: HttpMethod::Get,
                 path: PathTemplate::new("/repos/{owner}/{repo}/issues").unwrap(),
                 base_url: BaseUrl::new("https://api.github.com").unwrap(),
-                accept: AcceptHeader::new("application/json"),
+                accept: AcceptHeader::new("application/json").unwrap(),
                 response_wrapper_key: None,
             },
         }

crates/sqlize-core/src/catalog/types.rs

@@ -316,10 +316,15 @@ impl fmt::Display for HttpMethod {
 pub struct AcceptHeader(String);
 
 impl AcceptHeader {
-    pub fn new(s: impl Into<String>) -> Self {
+    pub fn new(s: impl Into<String>) -> Result<Self, Error> {
         let s = s.into();
-        assert!(!s.is_empty(), "AcceptHeader cannot be empty");
-        Self(s)
+        if s.is_empty() {
+            return Err(Error::InvalidAcceptHeader {
+                input: s,
+                reason: "cannot be empty",
+            });
+        }
+        Ok(Self(s))
     }
 
     pub fn as_str(&self) -> &str {

crates/sqlize-core/src/datafusion/arrow_convert.rs

@@ -312,7 +312,7 @@ mod tests {
                 method: HttpMethod::Get,
                 path: PathTemplate::new("/test").unwrap(),
                 base_url: BaseUrl::new("https://example.com").unwrap(),
-                accept: AcceptHeader::new("application/json"),
+                accept: AcceptHeader::new("application/json").unwrap(),
                 response_wrapper_key: None,
             },
         }

crates/sqlize-core/src/datafusion/provider.rs

@@ -215,7 +215,7 @@ mod tests {
                 method: HttpMethod::Get,
                 path: PathTemplate::new("/test/{id}").unwrap(),
                 base_url: BaseUrl::new("https://example.com").unwrap(),
-                accept: AcceptHeader::new("application/json"),
+                accept: AcceptHeader::new("application/json").unwrap(),
                 response_wrapper_key: None,
             },
         }

crates/sqlize-core/src/error.rs

@@ -20,6 +20,9 @@ pub enum Error {
     #[error("invalid base URL {input:?}: {reason}")]
     InvalidBaseUrl { input: String, reason: &'static str },
 
+    #[error("invalid accept header {input:?}: {reason}")]
+    InvalidAcceptHeader { input: String, reason: &'static str },
+
     // ---- Catalog lookup ----
     #[error("table {0} not found in catalog")]
     TableNotFound(TableName),

crates/sqlize-core/src/spec/table_gen.rs

@@ -165,7 +165,7 @@ fn try_build_table(
             method: HttpMethod::Get,
             path: path_template,
             base_url: base_url.clone(),
-            accept: crate::catalog::types::AcceptHeader::new(content_type),
+            accept: crate::catalog::types::AcceptHeader::new(content_type)?,
             response_wrapper_key: wrapper_key,
         },
     }))