Harden SuperPMI replay against missing data (#50307)

When generating disasm for an SPMI replay, we can call
`eeGetMethodFullName` for callees for which we are missing data.
Fix `MethodContext::repGetArgNext` to raise an appropriate exception,
and not crash, when it encounters missing data.

src/coreclr/ToolBox/superpmi/superpmi-shared/methodcontext.cpp

@@ -2685,8 +2685,11 @@ void MethodContext::dmpGetArgNext(DWORDLONG key, DWORDLONG value)
 }
 CORINFO_ARG_LIST_HANDLE MethodContext::repGetArgNext(CORINFO_ARG_LIST_HANDLE args)
 {
-    CORINFO_ARG_LIST_HANDLE temp = (CORINFO_ARG_LIST_HANDLE)GetArgNext->Get(CastHandle(args));
-    DEBUG_REP(dmpGetArgNext(CastHandle(args), CastHandle(temp)));
+    DWORDLONG key = CastHandle(args);
+    AssertCodeMsg(GetArgNext != nullptr, EXCEPTIONCODE_MC, "Didn't find %016llx", key);
+    AssertCodeMsg(GetArgNext->GetIndex(key) != -1, EXCEPTIONCODE_MC, "Didn't find %016llx", key);
+    CORINFO_ARG_LIST_HANDLE temp = (CORINFO_ARG_LIST_HANDLE)GetArgNext->Get(key);
+    DEBUG_REP(dmpGetArgNext(key, CastHandle(temp)));
     return temp;
 }
 void MethodContext::recGetMethodSig(CORINFO_METHOD_HANDLE ftn, CORINFO_SIG_INFO* sig, CORINFO_CLASS_HANDLE memberParent)