Add custom checks on the strategies if the object has the required specs

src/vehicles/HoseSystemFillArm.lua

@@ -59,13 +59,9 @@ function HoseSystemFillArm:load(savegame)
 
         self.fillArm = HoseSystemUtil.callStrategyFunction(self.fillArmStrategies, 'load', { self.xmlFile, HoseSystemFillArm.XML_KEY, self.fillArm })
 
-        if self.fillArm.needsTransfer ~= nill and not self.fillArm.needsTransfer and not SpecializationUtil.hasSpecialization(Fillable, self.specializations) then
-            HoseSystemUtil:log(HoseSystemUtil.ERROR, "Specialization HoseSystemFillArm needs the specialization Fillable")
-
+        if not HoseSystemUtil.callStrategyFunction(self.fillArmStrategies, 'prerequisitesPresent', { self }) then
             self.fillArm = {}
             self.fillArmStrategies = {}
-
-            return
         end
     end
 end

src/vehicles/strategies/HoseSystemArmStrategy.lua

@@ -2,6 +2,19 @@ HoseSystemArmStrategy = {}
 
 local HoseSystemArmStrategy_mt = Class(HoseSystemArmStrategy)
 
+---
+-- @param object
+--
+function HoseSystemArmStrategy:prerequisitesPresent(object)
+    if not SpecializationUtil.hasSpecialization(Fillable, object.specializations) then
+        HoseSystemUtil:log(HoseSystemUtil.ERROR, "Strategy HoseSystemArmStrategy needs the specialization Fillable")
+
+        return false
+    end
+
+    return true
+end
+
 ---
 -- @param object
 -- @param mt

src/vehicles/strategies/HoseSystemDockArmStrategy.lua

@@ -2,6 +2,19 @@ HoseSystemDockArmStrategy = {}
 
 local HoseSystemDockArmStrategy_mt = Class(HoseSystemDockArmStrategy)
 
+---
+-- @param object
+--
+function HoseSystemDockArmStrategy:prerequisitesPresent(object)
+    if not object.fillArm.needsTransfer and not SpecializationUtil.hasSpecialization(Fillable, object.specializations) then
+        HoseSystemUtil:log(HoseSystemUtil.ERROR, "Strategy HoseSystemDockArmStrategy needs the specialization Fillable")
+
+        return false
+    end
+
+    return true
+end
+
 ---
 -- @param object
 -- @param mt