Remove the warning on DynamicalODEProblems and instead raise an error if it's not a SecondOrderODEProblem (#133)

* Remove the warning and instead raise an error

Previously, we warned the user when they provide a DynamicalODEFunction to
inform them that we can not handle true DynamicalODEProblems, but only
SecondOrderODEProblems. Now, we instead check if the problem has the
SecondOrderODEProblem trait and raise an error if not.

* Apply JuliaFormatter.jl

* Fix the failing tests

* Remove escapes in error string to fix the tests for Julia 1.6

* Apply JuliaFormatter.jl

Author: nathanaelbosch

src/caches.jl

@@ -101,9 +101,6 @@ function OrdinaryDiffEq.alg_cache(
     end
 
     is_secondorder_ode = f isa DynamicalODEFunction
-    if is_secondorder_ode
-        @warn "Assuming that the given ODE is a SecondOrderODE. If this is not the case, e.g. because it is some other dynamical ODE, the solver will probably run into errors!"
-    end
 
     q = alg.order
     d = is_secondorder_ode ? length(u[1, :]) : length(u)

src/perform_step.jl

@@ -1,5 +1,17 @@
 # Called in the OrdinaryDiffEQ.__init; All `OrdinaryDiffEqAlgorithm`s have one
 function OrdinaryDiffEq.initialize!(integ, cache::GaussianODEFilterCache)
+    if integ.f isa DynamicalODEFunction &&
+       !(integ.sol.prob.problem_type isa SecondOrderODEProblem)
+        error(
+            """
+          The given problem is a `DynamicalODEProblem`, but not a `SecondOrderODEProblem`.
+          This can not be handled by ProbNumDiffEq.jl right now. Please check if the
+          problem can be formulated as a second order ODE. If not, please open a new
+          github issue!
+          """,
+        )
+    end
+
     if integ.opts.dense && !integ.alg.smooth
         error("To use `dense=true` you need to set `smooth=true`!")
     elseif !integ.opts.dense && integ.alg.smooth

src/solve.jl

@@ -7,11 +7,16 @@ function DiffEqBase.__init(
 ) where {uType,tType}
     @warn "The given problem is in out-of-place form. Since the algorithms in this package are written for in-place problems, it will be automatically converted."
     if prob.f isa DynamicalODEFunction
+        if !(prob.problem_type isa SecondOrderODEProblem)
+            error(
+                "DynamicalODEProblems that are not SecondOrderODEProblems are currently not supported",
+            )
+        end
         f1!(dv, v, u, p, t) = dv .= prob.f.f1(v, u, p, t)
-        f2!(du, v, u, p, t) = du .= prob.f.f2(v, u, p, t)
-        _prob = DynamicalODEProblem(
+        # f2!(du, v, u, p, t) = du .= prob.f.f2(v, u, p, t)
+        _prob = SecondOrderODEProblem(
             f1!,
-            f2!,
+            # f2!,
             prob.u0.x[1],
             prob.u0.x[2],
             prob.tspan,