Many times, we face similar error when declaring custom variables.

Example:

struct ContentView: View {
  var body: some View {
    header
  }

  var header: some View {
    Image("someimage")
    Text("Hello")
  }
}

Solution: We can use @ViewBuilder. This macro creates the content as closer and hence avoid us to give this error.

struct ContentView: View {
  var body: some View {
    header
  }

  @ViewBuilder
  var header: some View {
    Image("someimage")
    Text("Hello")
  }
}

PS: When we are searching for same error in search engine it is taking us to this solution so added this another case to help others.