[PL/TH2M] Adjust debug and warning messages

Same as in other processes.

ProcessLib/TH2M/TH2MFEM-impl.h

@@ -898,7 +898,6 @@ std::size_t TH2MLocalAssembler<
     if (name.starts_with("material_state_variable_") && name.ends_with("_ip"))
     {
         std::string const variable_name = name.substr(24, name.size() - 24 - 3);
-        DBUG("Setting material state variable '{:s}'", variable_name);
 
         // Using first ip data for solid material. TODO (naumov) move solid
         // material into element, store only material state in IPs.
@@ -910,10 +909,16 @@ std::size_t TH2MLocalAssembler<
                              { return iv.name == variable_name; });
             iv != end(internal_variables))
         {
+            DBUG("Setting material state variable '{:s}'", variable_name);
             return ProcessLib::setIntegrationPointDataMaterialStateVariables(
                 values, _ip_data, &IpData::material_state_variables,
                 iv->reference);
         }
+
+        WARN(
+            "Could not find variable {:s} in solid material model's "
+            "internal variables.",
+            variable_name);
     }
     return 0;
 }