Add error message when parameter file is invalid

packages/viewer/src/lib/server/parameters.ts

@@ -104,6 +104,10 @@ function loadRawParameters(
     rawParameter = rawParameterFromYaml(fs.readFileSync(nodePath, "utf-8")) as {
       [key: string]: unknown
     }
+    if (rawParameter === undefined) {
+      console.error(`Invalid parameter file at ${nodePath}`)
+      return undefined
+    }
     rawParameter.file_path = path.join(
       parametersRepository.parametersDir,
       ...relativeSplitPath,