Don't assert on tail calli, just do a non-tail call for now so the application will at least run (but potentially run out of stack)

Author: kg

src/coreclr/vm/interpexec.cpp

@@ -1879,10 +1879,10 @@ void InterpExecMethod(InterpreterFrame *pInterpreterFrame, InterpMethodContextFr
                     goto CALL_INTERP_METHOD;
                 }
 
-                // Interpreter-FIXME: INTOP_CALLI_TAIL
+                case INTOP_CALLI_TAIL:
                 case INTOP_CALLI:
                 {
-                    isTailcall = false;
+                    isTailcall = (*ip == INTOP_CALLI_TAIL);
                     returnOffset = ip[1];
                     callArgsOffset = ip[2];
                     int32_t calliFunctionPointerVar = ip[3];
@@ -1891,6 +1891,7 @@ void InterpExecMethod(InterpreterFrame *pInterpreterFrame, InterpMethodContextFr
                     CallStubHeader *pCallStub = (CallStubHeader*)pMethod->pDataItems[calliCookie];
                     ip += 5;
 
+                    // Interpreter-FIXME: isTailcall
                     InvokeCalliStub(LOCAL_VAR(calliFunctionPointerVar, PCODE), pCallStub, stack + callArgsOffset, stack + returnOffset);
                     break;
                 }
@@ -1991,7 +1992,7 @@ void InterpExecMethod(InterpreterFrame *pInterpreterFrame, InterpMethodContextFr
                         if (targetIp == NULL)
                         {
                             // If we didn't get the interpreter code pointer setup, then this is a method we need to invoke as a compiled method.
-                            // Interpreter-FIXME: What do we do for tail call?
+                            // Interpreter-FIXME: Implement tailcall via helpers, see https://github.com/dotnet/runtime/blob/main/docs/design/features/tailcalls-with-helpers.md
                             InvokeCompiledMethod(targetMethod, stack + callArgsOffset, stack + returnOffset, targetMethod->GetMultiCallableAddrOfCode(CORINFO_ACCESS_ANY));
                             break;
                         }