Fixed crashing when not passing negative key

koptilnya/input_system/cl_input.txt

@@ -27,7 +27,13 @@ function Input:noKeysHolding(axle)
 end
 
 function Input:getAxleValue(axle)
-    return (input.isKeyDown(axle.Positive) and 1 or 0) - (input.isKeyDown(axle.Negative) and 1 or 0)
+    local positiveValue = axle.Positive ~= nil and input.isKeyDown(axle.Positive)
+    local negativeValue = axle.Negative ~= nil and input.isKeyDown(axle.Negative)
+
+    print(positiveValue)
+    print(negativeValue)
+
+    return (positiveValue and 1 or 0) - (negativeValue and 1 or 0) -- (input.isKeyDown(axle.Positive) and 1 or 0) - (input.isKeyDown(axle.Negative) and 1 or 0)
 end
 
 function Input:_trySetTargetValue(key)
@@ -52,13 +58,18 @@ end
 
 function Input:_mapKeys(axles)
     for k, v in pairs(axles) do
-        self.keys[v.Negative] = {
-            Axle = k
-        }
+        if v.Negative ~= nil then
+            self.keys[v.Negative] = {
+                Axle = k
+            }
+        end
+
+        if v.Positive ~= nil then
+            self.keys[v.Positive] = {
+                Axle = k
+            }
+        end
 
-        self.keys[v.Positive] = {
-            Axle = k
-        }
     end
 end