SwiftUI Preview problem with 5.2 toolchain: module compiled with Swift 5.1.3 cannot be imported by the Swift 5.2 compiler

module compiled with Swift 5.1.3 cannot be imported by the Swift 5.2 compiler: /Users/x/Library/Developer/Xcode/DerivedData/MyApp-axhbbsfdahczcmbtnketjkuxxvkg/Build/Intermediates.noindex/Previews/MyApp WatchKit App/Products/Debug-watchsimulator/MyApp_WatchKit_Extension.swiftmodule/i386-apple-watchos-simulator.swiftmodule

Even after I deleted the DerivedDarta folder, Clean Build Folder, quit Xcode and restart Xcode, let it index, do Build (ok), but preview still fail with this same error.

Simulator runs fine

Why do 5.1.3 still there for the derive data? Anyway to fix this mismatch?

(I'm using the 5.2 toolchain to get pass this compiler bug: I'm stumped with this @ViewBuilder on var body: some View compile error: Cannot convert return expression of type '_ConditionalContent<Text, Text>' to return type 'some View')