fix: improve error messages (#502)

Author: ymc9

packages/runtime/src/enhancements/model-meta.ts

@@ -9,7 +9,7 @@ export function getDefaultModelMeta(): ModelMeta {
         // eslint-disable-next-line @typescript-eslint/no-var-requires
         return require('.zenstack/model-meta').default;
     } catch {
-        throw new Error('Model meta cannot be loaded');
+        throw new Error('Model meta cannot be loaded. Please make sure "zenstack generate" has been run.');
     }
 }
 

packages/runtime/src/enhancements/policy/index.ts

@@ -69,6 +69,8 @@ function getDefaultPolicy(): PolicyDef {
         // eslint-disable-next-line @typescript-eslint/no-var-requires
         return require('.zenstack/policy').default;
     } catch {
-        throw new Error('Policy definition cannot be loaded from default location');
+        throw new Error(
+            'Policy definition cannot be loaded from default location. Please make sure "zenstack generate" has been run.'
+        );
     }
 }