fix(compiler): reject malformed structured props

packages/compiler/src/codegen.ts

@@ -2414,7 +2414,7 @@ function generateComponent(ast: PageAst): string {
       );
     }
     decls.push(
-      `  const ${nameRefs.get(prop.name)}: ${prop.valueType ?? "any"} = __coerce(__p[${JSON.stringify(prop.name)}], (${resolveExpr(prop.default)}), ${JSON.stringify(runtimeTypeOf(prop.valueType))});`,
+      `  const ${nameRefs.get(prop.name)}: ${prop.valueType ?? "any"} = __coerce(__p[${JSON.stringify(prop.name)}], (${resolveExpr(prop.default)}), ${JSON.stringify(runtimeTypeOf(prop.valueType))}, ${JSON.stringify(prop.name)});`,
     );
   }
   if (!effectiveProps.some((prop) => prop.name === "attrs")) {
@@ -2504,7 +2504,7 @@ function generateComponent(ast: PageAst): string {
     );
   }
 
-  out.push(`function __coerce(v: any, def: any, declared: string = "unknown"): any {
+  out.push(`function __coerce(v: any, def: any, declared: string = "unknown", propName: string = "prop"): any {
   if (v === undefined || v === null) {
     return def;
   }
@@ -2529,14 +2529,14 @@ function generateComponent(ast: PageAst): string {
     if (typeof v === "string") {
       try {
         const parsed = JSON.parse(v);
-        return Array.isArray(parsed) ? parsed : def;
+        if (!Array.isArray(parsed)) throw new TypeError("Expected an array prop '" + propName + "'");
+        return parsed;
       } catch {
-        if (declared === "array") throw new TypeError("Expected an array prop");
-        return def;
+        throw new TypeError("Expected an array prop '" + propName + "'");
       }
     }
 
-    return def;
+    throw new TypeError("Expected an array prop '" + propName + "'");
   }
 
   if (declared === "object" || (def !== null && typeof def === "object")) {
@@ -2552,20 +2552,16 @@ function generateComponent(ast: PageAst): string {
       try {
         const parsed = JSON.parse(v);
 
-        return (
-          parsed !== null &&
-          typeof parsed === "object" &&
-          !Array.isArray(parsed)
-        )
-          ? parsed
-          : def;
+        if (parsed === null || typeof parsed !== "object" || Array.isArray(parsed)) {
+          throw new TypeError("Expected an object prop '" + propName + "'");
+        }
+        return parsed;
       } catch {
-        if (declared === "object") throw new TypeError("Expected an object prop");
-        return def;
+        throw new TypeError("Expected an object prop '" + propName + "'");
       }
     }
 
-    return def;
+    throw new TypeError("Expected an object prop '" + propName + "'");
   }
 
   if (declared === "bigint") return BigInt(v);

packages/compiler/test/__snapshots__/resilience.test.ts.snap

@@ -45,7 +45,7 @@ export interface CounterOutputs {
   "change"(value: number): void;
 }
 
-function __coerce(v: any, def: any, declared: string = "unknown"): any {
+function __coerce(v: any, def: any, declared: string = "unknown", propName: string = "prop"): any {
   if (v === undefined || v === null) {
     return def;
   }
@@ -70,14 +70,14 @@ function __coerce(v: any, def: any, declared: string = "unknown"): any {
     if (typeof v === "string") {
       try {
         const parsed = JSON.parse(v);
-        return Array.isArray(parsed) ? parsed : def;
+        if (!Array.isArray(parsed)) throw new TypeError("Expected an array prop '" + propName + "'");
+        return parsed;
       } catch {
-        if (declared === "array") throw new TypeError("Expected an array prop");
-        return def;
+        throw new TypeError("Expected an array prop '" + propName + "'");
       }
     }
 
-    return def;
+    throw new TypeError("Expected an array prop '" + propName + "'");
   }
 
   if (declared === "object" || (def !== null && typeof def === "object")) {
@@ -93,20 +93,16 @@ function __coerce(v: any, def: any, declared: string = "unknown"): any {
       try {
         const parsed = JSON.parse(v);
 
-        return (
-          parsed !== null &&
-          typeof parsed === "object" &&
-          !Array.isArray(parsed)
-        )
-          ? parsed
-          : def;
+        if (parsed === null || typeof parsed !== "object" || Array.isArray(parsed)) {
+          throw new TypeError("Expected an object prop '" + propName + "'");
+        }
+        return parsed;
       } catch {
-        if (declared === "object") throw new TypeError("Expected an object prop");
-        return def;
+        throw new TypeError("Expected an object prop '" + propName + "'");
       }
     }
 
-    return def;
+    throw new TypeError("Expected an object prop '" + propName + "'");
   }
 
   if (declared === "bigint") return BigInt(v);
@@ -264,7 +260,7 @@ function __wrnexusSerializeScopeValue(value: any): string {
 
 export function render(props: CounterProps = {} as CounterProps): string {
   const __p = props || {};
-  const label: string = __coerce(__p["label"], ("Count"), "string");
+  const label: string = __coerce(__p["label"], ("Count"), "string", "label");
   const __attrs = __restProps(__p, new Set(["label"]));
   let count = (0);
   const __scopeState = { "label": label, "count": count };

packages/compiler/test/compiler.test.ts

@@ -526,6 +526,17 @@ component NativeProps {
   );
 });
 
+test("malformed structured prop strings fail with the prop name", async () => {
+  const mod = await compileAndImport(`component StructuredProps {
+    props { items = [] options = {} }
+    view { <div></div> }
+  }`);
+  const render = mod.render as (props?: Record<string, unknown>) => string;
+
+  expect(() => render({ items: "not-json" })).toThrow("Expected an array prop 'items'");
+  expect(() => render({ options: "[]" })).toThrow("Expected an object prop 'options'");
+});
+
 test("parses a layout block", () => {
   const ast = parse(`
 layout AppLayout {