QtWebEngine confusion

There have been some puzzling commits lately around QtWebEngine:

1. !146 (merged)
2. 93374114
3. 90d78bd2

They have all seemed to miss the already existing switch ENABLE_WEBENGINE (https://invent.kde.org/office/kmymoney/-/blob/5.1/CMakeLists.txt#L246):

# check for optional QWebEngine
option(ENABLE_WEBENGINE "Enable QWebEngine" OFF)
if(ENABLE_WEBENGINE)
  find_package(Qt5WebEngineWidgets 5.8 REQUIRED)
  if(Qt5WebEngineWidgets_VERSION VERSION_GREATER 5.8.99 AND Qt5WebEngineWidgets_VERSION VERSION_LESS 5.9.3)
    message(WARNING "QWebEngine version ${Qt5WebEngineWidgets_VERSION} is known to be unstable with KMyMoney")
  endif()
else(ENABLE_WEBENGINE)
  find_package(KF5WebKit REQUIRED)
endif(ENABLE_WEBENGINE)

(that is from 5.1 branch, but was since dropped in master branch)

Having seen this,

• how did ArchLinux require 1) to fix their build, but was still fine after the change in 2)? Did anyone actually look at the build.log error messages?
• if AppImage required 2) to fix build, how did it ever work with -DENABLE_WEBENGINE set as default (still in 5.1 branch)? See also https://invent.kde.org/office/kmymoney/-/blob/5.1/packaging/linux/appimage/build-kmymoney.sh#L42

I propose to revert 151357b7 in 5.1, nothing needed fixing here from my POV.

Coming back to master branch, does that mean commit a2031813 ("Migrate to QTextBrowser") was not fully complete?

Okay, after reverting the bogus dependencies in master branch, I can see now an error that is caused by alkimia:

CMake Error at /usr/lib64/cmake/LibAlkimia5-8.1/LibAlkimia5Targets.cmake:65 (set_target_properties):
  The link interface of target "Alkimia::alkimia" contains:

    Qt5::WebEngineWidgets

  but the target was not found.  Possible reasons include:

    * There is a typo in the target name.
    * A find_package call is missing for an IMPORTED target.
    * An ALIAS target is missing.

Call Stack (most recent call first):
  /usr/lib64/cmake/LibAlkimia5-8.1/LibAlkimia5Config.cmake:66 (include)
  CMakeLists.txt:125 (find_package)

But that is an error that needs to be fixed in alkimia and not kmymoney. And if alkimia is built without QtWebEngine, kmymoney also builds fine without it or QtWebKit, both of which are no longer used by master branch since the aforementioned commit.