Xcode build system crashing - xcode

Question

Xcode 10.1
Xcode Product->Build works fine
Project is OLD. Migrated from pre-Xcode 9.
No tests in the project
Add unit test target (containing only the empty sample test)
Product->Test fails and crashes the build system
It seems to be caused by a link naturally created by the build from the DerivedData to the /tmp directory.
Xcode compiler output:
error: unexpected explicit output: '<TRIGGER: SymLink /Users/bill.shirley/Library/Developer/Xcode/DerivedData/Projects-aacmhfqthnovqgecjzbjrmjgtxae/Build/Products/Debug-iphoneos/ios1.app /tmp/Kevin.dst/Applications/ios1.app>'
error: unexpected service error: The Xcode build system has crashed. Please close and reopen your workspace.
related but unhelpful Xcode: invalid symlink error when trying to run app in iOS simulator
I've attempted lots of quit and restart Xcode (required), deleting of derived data, making clean, deleting simulators, rebooting with everything clean and reading empty test. To no avail.
I would love to rebuild this project from scratch, but it's massive and I don't have (i.e. want to make) the time currently.
Workaround 2: no testing.
Edit: Previously Unstated.
This app uses Cocoapods.
I tried the suggestion enter link description here, using items 2-6, running pod install when changes are made (and Podfile update) and it changed to a
ld: -bundle_loader can only be used with -bundle
clang: error: linker command failed with exit code 1 (use -v to see invocation)
invocation is:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -arch x86_64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator12.1.sdk -L/Users/bill.shirley/Dev/ios/Build/Products/Debug-iphonesimulator -L/Users/bill.shirley/Dev/ios/Projects/Kevin/../../Pods/CardIO/CardIO -F/Users/bill.shirley/Dev/ios/Build/Products/Debug-iphonesimulator -F/Users/bill.shirley/Dev/ios/Build/Products/Debug-iphonesimulator/Calendar -F/Users/bill.shirley/Dev/ios/Build/Products/Debug-iphonesimulator/FirebaseCore -F/Users/bill.shirley/Dev/ios/Build/Products/Debug-iphonesimulator/FirebaseMessaging -F/Users/bill.shirley/Dev/ios/Build/Products/Debug-iphonesimulator/GoogleUtilities -F/Users/bill.shirley/Dev/ios/Build/Products/Debug-iphonesimulator/Heartland-iOS-SDK -F/Users/bill.shirley/Dev/ios/Build/Products/Debug-iphonesimulator/IGListKit -F/Users/bill.shirley/Dev/ios/Build/Products/Debug-iphonesimulator/IOForm -F/Users/bill.shirley/Dev/ios/Build/Products/Debug-iphonesimulator/OpenCV -F/Users/bill.shirley/Dev/ios/Build/Products/Debug-iphonesimulator/Protobuf -F/Users/bill.shirley/Dev/ios/Build/Products/Debug-iphonesimulator/XMLDictionary -F/Users/bill.shirley/Dev/ios/Build/Products/Debug-iphonesimulator/nanopb -F/Users/bill.shirley/Dev/ios/Projects/Kevin/../../Pods/Crashlytics/iOS -F/Users/bill.shirley/Dev/ios/Projects/Kevin/../../Pods/Fabric/iOS -F/Users/bill.shirley/Dev/ios/Projects/Kevin/../../Pods/FirebaseAnalytics/Frameworks -F/Users/bill.shirley/Dev/ios/Projects/Kevin/../../Pods/FirebaseInstanceID/Frameworks -F/Users/bill.shirley/Dev/ios/Projects/Kevin/../../Pods/GoogleAppMeasurement/Frameworks -F/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/Library/Frameworks -filelist /Users/bill.shirley/Dev/ios/Build/Intermediates.noindex/Kevin.build/Debug-iphonesimulator/ios1Tests.build/Objects-normal/x86_64/ios1Tests.LinkFileList -Xlinker -rpath -Xlinker #executable_path/Frameworks -Xlinker -rpath -Xlinker #loader_path/Frameworks -Xlinker -rpath -Xlinker #executable_path/Frameworks -Xlinker -rpath -Xlinker #loader_path/Frameworks -mios-simulator-version-min=12.1 -dead_strip -bundle_loader /Users/bill.shirley/Dev/ios/Build/Products/Debug-iphonesimulator/ios1.app/ios1 -Xlinker -object_path_lto -Xlinker /Users/bill.shirley/Dev/ios/Build/Intermediates.noindex/Kevin.build/Debug-iphonesimulator/ios1Tests.build/Objects-normal/x86_64/ios1Tests_lto.o -Xlinker -export_dynamic -Xlinker -no_deduplicate -Xlinker -objc_abi_version -Xlinker 2 -fobjc-link-runtime -L/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator -Xlinker -add_ast_path -Xlinker /Users/bill.shirley/Dev/ios/Build/Intermediates.noindex/Kevin.build/Debug-iphonesimulator/ios1Tests.build/Objects-normal/x86_64/ios1Tests.swiftmodule -lstdc++ -ObjC -lCardIO -lc++ -lopencv_core -lopencv_imgproc -lsqlite3 -lz -framework AVFoundation -framework Accelerate -framework AudioToolbox -framework Calendar -framework CoreMedia -framework CoreVideo -framework Crashlytics -framework FIRAnalyticsConnector -framework Fabric -framework FirebaseAnalytics -framework FirebaseCore -framework FirebaseCoreDiagnostics -framework FirebaseInstanceID -framework FirebaseMessaging -framework Foundation -framework GoogleAppMeasurement -framework GoogleUtilities -framework Heartland_iOS_SDK -framework IGListKit -framework IOForm -framework MobileCoreServices -framework OpenGLES -framework Protobuf -framework QuartzCore -framework Security -framework StoreKit -framework SystemConfiguration -framework UIKit -framework XMLDictionary -framework nanopb -framework opencv2 -framework XCTest -Xlinker -sectcreate -Xlinker __TEXT -Xlinker __entitlements -Xlinker /Users/bill.shirley/Dev/ios/Build/Intermediates.noindex/Kevin.build/Debug-iphonesimulator/ios1Tests.build/ios1Tests.xctest-Simulated.xcent -framework Pods_ios1Tests -Xlinker -dependency_info -Xlinker /Users/bill.shirley/Dev/ios/Build/Intermediates.noindex/Kevin.build/Debug-iphonesimulator/ios1Tests.build/Objects-normal/x86_64/ios1Tests_dependency_info.dat -o /Users/bill.shirley/Dev/ios/Build/Products/Debug-iphonesimulator/ios1.app/PlugIns/ios1Tests.xctest/ios1Tests