Make the error return more explicit when an SBValue has no value.

llvm-svn: 251722
diff --git a/lldb/source/API/SBValue.cpp b/lldb/source/API/SBValue.cpp
index 6a55880..a8584c5 100644
--- a/lldb/source/API/SBValue.cpp
+++ b/lldb/source/API/SBValue.cpp
@@ -1425,7 +1425,10 @@
 SBValue::GetSP (ValueLocker &locker) const
 {
     if (!m_opaque_sp || !m_opaque_sp->IsValid())
+    {
+        locker.GetError().SetErrorString("No value");
         return ValueObjectSP();
+    }
     return locker.GetLockedSP(*m_opaque_sp.get());
 }