minor fixes

Author: rbeeli

src/account.jl

@@ -132,7 +132,7 @@ Determines if the account has non-zero exposure to the given instrument
 in the given direction (`Buy`, `Sell`).
 """
 @inline function is_exposed_to(acc::Account, inst::Instrument, dir::TradeDir.T)
-    trade_dir(get_position(acc, inst)) == sign(dir)
+    sign(trade_dir(get_position(acc, inst))) == sign(dir)
 end
 
 """

src/collectors.jl

@@ -78,7 +78,7 @@ mutable struct MinValue{T}
 end
 
 function min_value_collector(::Type{T}) where {T}
-    mv = MinValue{T}(DateTime(0), 1e50)
+    mv = MinValue{T}(DateTime(0), typemax(T))
 
     @inline function collector(dt::DateTime, value::T)
         if value < mv.min_value

src/exchange_rates.jl

@@ -30,7 +30,7 @@ Supports spot exchange rates between assets.
 """
 mutable struct SpotExchangeRates{CData} <: ExchangeRates{CData}
     const rates::Vector{Vector{Float64}} # rates[from][to] using internal index
-    const indices::Dict{Cash{CData},UInt} # cash object -> index
+    const indices::Dict{Cash{CData},Int} # cash object -> index
     const assets::Vector{Cash{CData}}
 
     function SpotExchangeRates(