protocol APIResource {
    associatedtype ModelType: Decodable
 
    var baseURL: URL? { get }
}
 
extension APIResource {
    var baseURL: URL? {
        return nil
    }
}
 
class BaseResource<T: Decodable>: APIResource {
    typealias ModelType = T
}

1. Apple Swift version 5.2.2 (swiftlang-1103.0.32.6 clang-1103.0.32.51)
2. While generating SIL witness table protocol conformance to 'APIResource' (at /.../NetworkManager/Service/APIResource.swift:157:1) for type 'BaseResource<T>' (declared at [/.../NetworkManager/Service/APIResource.swift:170:1 - line:172:1] RangeText="class BaseResource<T: Decodable>: APIResource {
    typealias ModelType = T
")
3. While generating protocol witness thunk SIL function "@$s14NetworkManager12BaseResourceCyqd__GAA12APIResourceA2aEP7baseURL10Foundation0G0VSgvgTW".
 for getter for baseURL (at /.../NetworkManager/Service/APIResource.swift:165:9)
0  swift                    0x000000010a3d34ea PrintStackTraceSignalHandler(void*) + 42
1  swift                    0x000000010a3d2cc0 SignalHandler(int) + 352
2  libsystem_platform.dylib 0x00007fff73aa042d _sigtramp + 29
3  libsystem_platform.dylib 0x000000010bbb1400 _sigtramp + 2551255024
4  swift                    0x00000001065d941d swift::Lowering::SILGenModule::useConformance(swift::ProtocolConformanceRef) + 173
5  swift                    0x00000001065db0fd swift::Lowering::SILGenModule::emitLazyConformancesForFunction(swift::SILFunction*) + 1277
6  swift                    0x000000010662fa9e swift::Lowering::SILGenModule::emitProtocolWitness(swift::ProtocolConformanceRef, swift::SILLinkage, swift::IsSerialized_t, swift::SILDeclRef, swift::SILDeclRef, swift::Lowering::IsFreeFunctionWitness_t, swift::Witness) + 2702
7  swift                    0x000000010662ef96 (anonymous namespace)::SILGenWitnessTable<(anonymous namespace)::SILGenConformance>::addMethod(swift::SILDeclRef) + 902
8  swift                    0x000000010662ebfb void llvm::function_ref<void (swift::AccessorDecl*)>::callback_fn<swift::SILWitnessVisitor<(anonymous namespace)::SILGenConformance>::visitAbstractStorageDecl(swift::AbstractStorageDecl*)::'lambda'(swift::AccessorDecl*)>(long, swift::AccessorDecl*) + 267
9  swift                    0x000000010713fe22 swift::AbstractStorageDecl::visitExpectedOpaqueAccessors(llvm::function_ref<void (swift::AccessorKind)>) const + 322
10 swift                    0x000000010662e33a swift::SILWitnessVisitor<(anonymous namespace)::SILGenConformance>::visitProtocolDecl(swift::ProtocolDecl*) + 1274
11 swift                    0x000000010662daf6 swift::Lowering::SILGenModule::getWitnessTable(swift::NormalProtocolConformance*) + 550
12 swift                    0x00000001066336d8 (anonymous namespace)::SILGenType::emitType() + 6840
13 swift                    0x0000000106544152 swift::ASTVisitor<swift::Lowering::SILGenModule, void, void, void, void, void, void>::visit(swift::Decl*) + 82
14 swift                    0x000000010654331c swift::Lowering::SILGenModule::emitSourceFile(swift::SourceFile*) + 1356
15 swift                    0x000000010654539e swift::SILModule::constructSIL(swift::ModuleDecl*, swift::Lowering::TypeConverter&, swift::SILOptions&, swift::FileUnit*) + 1438
16 swift                    0x0000000106125131 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 48065
17 swift                    0x000000010609cf53 main + 1283
18 libdyld.dylib            0x00007fff738a77fd start + 1
19 libdyld.dylib            0x0000000000000060 start + 2356512868
error: Segmentation fault: 11 (in target 'NetworkManager' from project 'NetworkManager')