diff --git a/src/base/simulation_results.jl b/src/base/simulation_results.jl
index 3c9efe157..75ac4a5ef 100644
--- a/src/base/simulation_results.jl
+++ b/src/base/simulation_results.jl
@@ -70,10 +70,17 @@ function post_proc_state_series(
 )
     global_state_index = get_global_index(res)
     if !haskey(global_state_index, ref[1])
-        @error "$(keys(global_state_index))"
-        error("State $(ref[2]) device $(ref[1]) not found in the system. ")
+        available_devices = join(keys(global_state_index), ", ")
+        error("Device $(ref[1]) not found. Available devices: $available_devices")
     end
-    ix = get(global_state_index[ref[1]], ref[2], 0)
+
+    state_dict = global_state_index[ref[1]]
+    if !haskey(state_dict, ref[2])
+        available_states = join(keys(state_dict), ", ")
+        error("State $(ref[2]) not found in device $(ref[1]). Available states: $available_states")
+    end
+
+    ix = state_dict[ref[2]]
     return _post_proc_state_series(get_solution(res), ix, dt, unique_timestamps)
 end
 
diff --git a/src/post_processing/post_proc_generator.jl b/src/post_processing/post_proc_generator.jl
index 731ed4e8b..2ceb8d5eb 100644
--- a/src/post_processing/post_proc_generator.jl
+++ b/src/post_processing/post_proc_generator.jl
@@ -1056,7 +1056,7 @@ function _mechanical_torque(
     name::String,
     res::SimulationResults,
     dt::Union{Nothing, Float64, Vector{Float64}},
-    unique_timestamps::Bool,
+    unique_timestamps::Bool = true,
 )
     # TODO: This will not plot correctly when changing P_ref in a callback
     ts, _ = _post_proc_state_series(res.solution, 1, dt, unique_timestamps)
@@ -1076,7 +1076,7 @@ function _mechanical_torque(
     name::String,
     res::SimulationResults,
     dt::Union{Nothing, Float64, Vector{Float64}},
-    unique_timestamps::Bool,
+    unique_timestamps::Bool = true,
 )
     # Get params
     Tc = PSY.get_Tc(tg)
@@ -1105,7 +1105,7 @@ function _mechanical_torque(
     name::String,
     res::SimulationResults,
     dt::Union{Nothing, Float64, Vector{Float64}},
-    unique_timestamps::Bool,
+    unique_timestamps::Bool = true,
 )
     # TODO: This will not plot correctly when changing P_ref in a callback
     # Get params
@@ -1135,7 +1135,7 @@ function _mechanical_torque(
     name::String,
     res::SimulationResults,
     dt::Union{Nothing, Float64, Vector{Float64}},
-    unique_timestamps::Bool,
+    unique_timestamps::Bool = true,
 )
     # TODO: This will not plot correctly when changing P_ref in a callback
     # Get params
@@ -1171,7 +1171,7 @@ function _mechanical_torque(
     name::String,
     res::SimulationResults,
     dt::Union{Nothing, Float64, Vector{Float64}},
-    unique_timestamps::Bool,
+    unique_timestamps::Bool = true,
 )
     # Get params
     D_turb = PSY.get_D_turb(tg)
@@ -1192,7 +1192,7 @@ function _mechanical_torque(
     name::String,
     res::SimulationResults,
     dt::Union{Nothing, Float64},
-    unique_timestamps::Bool,
+    unique_timestamps::Bool = true,
 )
     ts, x_a3 = post_proc_state_series(res, (name, :x_a3), dt, unique_timestamps)
     return ts, x_a3
@@ -1222,7 +1222,7 @@ function _mechanical_torque(
     name::String,
     res::SimulationResults,
     dt::Union{Nothing, Float64, Vector{Float64}},
-    unique_timestamps::Bool,
+    unique_timestamps::Bool = true,
 )
     # Get params
     q_nl = PSY.get_q_nl(tg)
@@ -1249,7 +1249,7 @@ function _mechanical_torque(
     name::String,
     res::SimulationResults,
     dt::Union{Nothing, Float64, Vector{Float64}},
-    unique_timestamps::Bool,
+    unique_timestamps::Bool = true,
 )
     # Get params
     D_turb = PSY.get_D_turb(tg)
@@ -1281,7 +1281,7 @@ function _mechanical_torque(
     name::String,
     res::SimulationResults,
     dt::Union{Nothing, Float64, Vector{Float64}},
-    unique_timestamps::Bool,
+    unique_timestamps::Bool = true,
 )
     # Get params
     D = PSY.get_D(tg)