Merge pull request #1148 from AayushSabharwal/as/promote-ambig

fix: fix method ambiguity in `promote_u0` in MonteCarloExt

Author: ChrisRackauckas

ext/DiffEqBaseMonteCarloMeasurementsExt.jl

@@ -24,6 +24,12 @@ function DiffEqBase.promote_u0(u0,
     eltype(p).(u0)
 end
 
+function DiffEqBase.promote_u0(::Nothing,
+        p::AbstractArray{<:MonteCarloMeasurements.AbstractParticles},
+        t0)
+    return nothing
+end
+
 DiffEqBase.value(x::Type{MonteCarloMeasurements.AbstractParticles{T, N}}) where {T, N} = T
 DiffEqBase.value(x::MonteCarloMeasurements.AbstractParticles) = mean(x.particles)
 function DiffEqBase.unitfulvalue(x::Type{MonteCarloMeasurements.AbstractParticles{