Index: source/Commands/CommandObjectRegister.cpp
===================================================================
--- source/Commands/CommandObjectRegister.cpp
+++ source/Commands/CommandObjectRegister.cpp
@@ -171,7 +171,9 @@
           set_idx = m_command_options.set_indexes[i]->GetUInt64Value(UINT32_MAX,
                                                                      nullptr);
           if (set_idx < reg_ctx->GetRegisterSetCount()) {
-            if (!DumpRegisterSet(m_exe_ctx, strm, reg_ctx, set_idx)) {
+            if (DumpRegisterSet(m_exe_ctx, strm, reg_ctx, set_idx)) {
+              result.SetStatus(eReturnStatusSuccessFinishResult);
+            } else {
               if (errno)
                 result.AppendErrorWithFormatv("register read failed: {0}\n",
                                               llvm::sys::StrError());
@@ -196,6 +198,7 @@
           // registers.
           DumpRegisterSet(m_exe_ctx, strm, reg_ctx, set_idx,
                           !m_command_options.dump_all_sets.GetCurrentValue());
+          result.SetStatus(eReturnStatusSuccessFinishResult);
         }
       }
     } else {
@@ -220,7 +223,9 @@
           reg_info = reg_ctx->GetRegisterInfoByName(arg_str);
 
           if (reg_info) {
-            if (!DumpRegister(m_exe_ctx, strm, reg_ctx, reg_info))
+            if (DumpRegister(m_exe_ctx, strm, reg_ctx, reg_info))
+              result.SetStatus(eReturnStatusSuccessFinishResult);
+            else
               strm.Printf("%-12s = error: unavailable\n", reg_info->name);
           } else {
             result.AppendErrorWithFormat("Invalid register name '%s'.\n",
Index: source/Interpreter/CommandInterpreter.cpp
===================================================================
--- source/Interpreter/CommandInterpreter.cpp
+++ source/Interpreter/CommandInterpreter.cpp
@@ -68,6 +68,7 @@
 #include "lldb/Target/Thread.h"
 
 #include "lldb/Utility/CleanUp.h"
+#include "lldb/Utility/LLDBAssert.h"
 
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallString.h"
@@ -1675,6 +1676,7 @@
           remainder.c_str());
 
     cmd_obj->Execute(remainder.c_str(), result);
+    lldbassert(eReturnStatusStarted != result.GetStatus());
   } else {
     // We didn't find the first command object, so complete the first argument.
     Args command_args(command_string);