Error on non-finite values when debugging systems

Author: hersle

src/debugging.jl

@@ -7,18 +7,23 @@ struct LoggedFun{F}
     f::F
     args::Any
 end
+LoggedFunctionException(lf::LoggedFun, args, msg) = LoggedFunctionException(
+    "Function $(lf.f)($(join(lf.args, ", "))) " * msg * " with input" *
+    join("\n  " .* string.(lf.args .=> args)) # one line for each "var => val" for readability
+)
 Base.showerror(io::IO, err::LoggedFunctionException) = print(io, err.msg)
 Base.nameof(lf::LoggedFun) = nameof(lf.f)
 SymbolicUtils.promote_symtype(::LoggedFun, Ts...) = Real
 function (lf::LoggedFun)(args...)
-    try
-        return lf.f(args...) # try to call with numerical input, as usual
+    val = try
+        lf.f(args...) # try to call with numerical input, as usual
     catch err
-        throw(LoggedFunctionException(
-            "Function $(lf.f)($(join(lf.args, ", "))) errors with input" *
-            join("\n  " .* string.(lf.args .=> args)) # one line for each "var => val" for readability
-        )) # Julia automatically attaches original error message
+        throw(LoggedFunctionException(lf, args, "errors")) # Julia automatically attaches original error message
     end
+    if !isfinite(val)
+        throw(LoggedFunctionException(lf, args, "output non-finite value $val"))
+    end
+    return val
 end
 
 function logged_fun(f, args...)

src/systems/abstractsystem.jl

@@ -2266,18 +2266,14 @@ Replace functions with singularities with a function that errors with symbolic
 information. E.g.
 
 ```julia-repl
-julia> sys = debug_system(sys)
+julia> sys = debug_system(complete(sys))
 
-julia> sys = complete(sys)
-
-julia> prob = ODEProblem(sys, [1.0, 0.0], (0.0, 1.0))
+julia> prob = ODEProblem(sys, [0.0, 2.0], (0.0, 1.0))
 
 julia> prob.f(prob.u0, prob.p, 0.0)
-ERROR: Function log(-cos(Q(t))) errors with input
-  -cos(Q(t)) => -1.0
-Stacktrace:
-  [1] (::ModelingToolkit.LoggedFun{typeof(log)})(num_args::Float64)
-  ...
+ERROR: Function /(1, sin(P(t))) output non-finite value Inf with input
+  1 => 1
+  sin(P(t)) => 0.0
 ```
 """
 function debug_system(sys::AbstractSystem)

test/odesystem.jl

@@ -939,7 +939,7 @@ testdict = Dict([:name => "test"])
 sys = complete(debug_system(sys))
 prob = ODEProblem(sys, [], (0.0, 1.0))
 @test_throws "log(-cos(Q(t))) errors" prob.f([1, 0], prob.p, 0.0)
-@test prob.f([0, 2], prob.p, 0.0)[1] == 1 / 0
+@test_throws "/(1, sin(P(t))) output non-finite value" prob.f([0, 2], prob.p, 0.0)
 
 let
     @variables x(t) = 1